When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
All, I have a 1969 Cutlass 4dr hardtop and found out the rearend needs to be rebuilt. Should I change to limited slip, posi, or leave it factory? Trying to keep mostly original. Also will it lessen the worth of the car? Thank you
All, I have a 1969 Cutlass 4dr hardtop and found out the rearend needs to be rebuilt. Should I change to limited slip, posi, or leave it factory? Trying to keep mostly original. Also will it lessen the worth of the car? Thank you
Evidently you didn't validate this yourself I suspect. When you found out (by someone/some place) what exactly did they mean by the rear end needs to be rebuilt? Is it only the differential, are they also referring to axles? If your intention is to keep it mostly original, then rebuild to original.
Ask yourself how many 4 doors were sold back then and how many were optioned with limited slip rears? I have to think very few. Ignore the value question. That won't even come into play here. Unless you're making power and planning on trying to launch the car hard enough to break the tires loose or slide the *** end around, why even consider adding limited slip?
I had a 71 4 dr w/ ltd slip, 4v, vinyl roof, “radio delete,” power locks, manual windows, power bench, hood lock, lighting group, remote trunk release & A/C. I think the salesman musta spilled coffee on the order sheet!
Rear axle ended up in someone’s hot rod build.
OP would likely be best to source a “ready to install” rear end, ltd slip or not unless it matters to him. A reputedly good peg legger can be found around me (CT) for ~$250. Ltd slip 5-10 times more.
Thank you everyone for your response. It’s my first vintage car so I plan on keeping it for a while and fix whats broken. I don’t plan on racing it. I may eventually add dual exhaust but looks like I will be rebuilding or replacing the original transmission by next season.
My friend just replaced the rear axle bearings and seals. It was still making noise and brought it to a garage and they said the carrier bearings and pinion bearings are bad. The car sat for a good amount of time. Sorry for not being specific.
My friend just replaced the rear axle bearings and seals. It was still making noise and brought it to a garage and they said the carrier bearings and pinion bearings are bad. The car sat for a good amount of time. Sorry for not being specific.
Congratulations on your 1st Oldsmobile classic. Enjoy yourself.
Before we get in too deep, can you verify for us where the car was built? I ask because if it's local to NY, it could be a Canadian car, which would have a different differential from a US build. This will affect how you can best proceed -- I'll explain why after you respond.
Last edited by BangScreech4-4-2; Jul 25, 2025 at 06:39 PM.
Should I change to limited slip, posi, or leave it factory? Trying to keep mostly original. Also will it lessen the worth of the car?
Originally Posted by Spence1
I don’t plan on racing it. I may eventually add dual exhaust but looks like I will be rebuilding or replacing the original transmission by next season.
Posi not so important as far as more oomph at this stage. But duals, 4bbl, a higher numerical rear gear ratio, and above all a TH350, yes !
Your car with the TH350 is 1 second quicker than with the Jetaway. And 2 seconds quicker with a 4bbl, dual exhaust, and TH350. Now increase the gear ratio number from 2.56 to 3.55 and she is another 1/2 second quicker. Posi is not necessary at this point. Limited slip much like bucket seats, console, gauges, was not standard on many an original muscle car. They fall more into the wants than needs category. Original 442s, GTOs, SS Chevelles, etc, did not come standard with posi. And they are all quicker than your car will be after the mods I mentioned. 20 years later modern muscle like Grand Nationals did not come standard posi, and were as quick as original muscle. 30 years later 4th generation LS1 Camaros came standard posi, and they were as quick as peak original muscle. So I guess what I am saying is eventually it will make sense to go there...
If the rear needs the rebuild going posi is a big time "might as well". But something to keep in mind with limited slip. It's great for track performance but in my personal experience it makes driving in inclement weather more challenging... If she's just a nice weather toy, no worries. But the 66 442 I had that was 3.23 posi and Jetaway was frightening in snow, sleet, etc. I managed because I've been driving the same type of car for decades. But it still made me very uncomfortable. I avoided the scenario like the plague after that. The *** would continuously kick out towards the parked cars with cautions driving... Meanwhile my 67 open rear Cutlass drove dead straight in worse conditions, even when heavy footed...
Phil - Good point regarding limited slip on snow/ice covered roads/highways. Requires a knack for feathering the pedal. Doesn't take much for the *** end to break away.
Posi not so important as far as more oomph at this stage. But duals, 4bbl, a higher numerical rear gear ratio, and above all a TH350, yes !
Your car with the TH350 is 1 second quicker than with the Jetaway. And 2 seconds quicker with a 4bbl, dual exhaust, and TH350. Now increase the gear ratio number from 2.56 to 3.55 and she is another 1/2 second quicker. Posi is not necessary at this point. Limited slip much like bucket seats, console, gauges, was not standard on many an original muscle car. They fall more into the wants than needs category. Original 442s, GTOs, SS Chevelles, etc, did not come standard with posi. And they are all quicker than your car will be after the mods I mentioned. 20 years later modern muscle like Grand Nationals did not come standard posi, and were as quick as original muscle. 30 years later 4th generation LS1 Camaros came standard posi, and they were as quick as peak original muscle. So I guess what I am saying is eventually it will make sense to go there...
If the rear needs the rebuild going posi is a big time "might as well". But something to keep in mind with limited slip. It's great for track performance but in my personal experience it makes driving in inclement weather more challenging... If she's just a nice weather toy, no worries. But the 66 442 I had that was 3.23 posi and Jetaway was frightening in snow, sleet, etc. I managed because I've been driving the same type of car for decades. But it still made me very uncomfortable. I avoided the scenario like the plague after that. The *** would continuously kick out towards the parked cars with cautions driving... Meanwhile my 67 open rear Cutlass drove dead straight in worse conditions, even when heavy footed...
That is more a tire issue, than the limited slip in the snow.
Been driving in the snow for 5 decades with limited slip rears, and never have I had an issue. The car only slides sideways when the tires are sliding.
Tire issue. not a limited diff issue. All seasons are not winter tires.
Hopefully get to drive it this summer. The garage told me limited slip would be an additional $900 added to the carrier bearings and pinion bearings. I do like the car.
Been driving in the snow for 5 decades with limited slip rears, and never have I had an issue. The car only slides sideways when the tires are sliding.
Tire issue. not a limited diff issue. All seasons are not winter tires.
When was a kid living in NJ in the mid 70's, I/we used to run snow tires, some with studs. Never had an issue getting stuck and went everywhere. Usually got around 4-5 seasons out of them.
Ah yes, the Philly winters, I remember them well. I'm a native NE Philly kid - every winter from the 80's until I moved away in the 90's, if I wasn't driving sideways on the black ice I was staring at 5 ft mounds of snow on top of my car at the curb in front of my house that the city plows piled on top of curbside-parked cars as they came down the streets.
None of the cars I owned during my Philly days had posi, but there are times I recall when it probably would have helped a lot. I'd vote every time for having it now, funds permitting.
For my '72, I rebuilt the rear with a Yukon 3.08 posi (up from the original 2.56 non-posi gear set) and it's a great street/highway combo.
Been driving in the snow for 5 decades with limited slip rears, and never have I had an issue. The car only slides sideways when the tires are sliding.
Tire issue. not a limited diff issue. All seasons are not winter tires.
And if they are sliding, you counter-steer.
This is a perfect example of why you should learn how a slide feels, and more importantly how to correct for it.
This is a perfect example of why you should learn how a slide feels, and more importantly how to correct for it.
Ideally in a snowy empty parking lot.
And I can't understand why anyone would want only one wheel drive in snow, mud, soft ground or down the highway. Two wheel drive (Anti Spin) will get you through more than one wheel spin.
This is a perfect example of why you should learn how a slide feels, and more importantly how to correct for it.
Ideally in a snowy empty parking lot.
Yup. on snow, in a slide, slam it in R and gun it. it straight'ns right out.
But crawling up a road slowly if the rear is drifting towards parked cars you got the wrong tires on.
And I can't understand why anyone would want only one wheel drive in snow, mud, soft ground or down the highway. Two wheel drive (Anti Spin) will get you through more than one wheel spin.
Some only see snow once a year if ever. So they have "all season tires that are crap in the snow, so the rear drifting as both tires spin/slide freaks many out. Those that are used to snow and ice know, take off the all seasons and on go the snow tires and welcome the grip of both wheels moving you.
I'd hazzard a guess that driving in snow isn't an issue for most of the classic olds cars today. But same holds true even today on your daily even if it is AWD. all season tires or worse performance all seasons suck in the snow. A set of take off wheels and winter tires is always cheaper than your deductable and /or a totalled vehicle.
I don't have to swap tires as I have what us rustbelters call the winter beater. Come late fall it becomes the daily. AWD v8 jeep and snow tires on all 4 corners.
I’ll take limited slip for challenging conditions. Less spinning, less chance of breakaway, ability to steer with the throttle as well as the steering wheel. Gotta have a feel for the car and not “pull a Mustang” not knowing when to feather or let up on the gas pedal, ie “whiskey throttle.” I’ve maintained forward motion at times driving straight with 30* yaw.
That said, IMO, tires are infinitely more important than peg legs vs ltd slip vs variations of 4WD/AWD. I have always believed in 4wd (generically) allowing one to get going fast enough to do REAL damage when they can’t turn or stop due to ill suited or worn tires. I can’t recount all the “4wd follies” I’ve witnessed or received into the body shop over the decades.
My kid’s red 70 w/ ltd slip & snows on all 4 corners never had a problem, daughter drove a peg leg Volvo 240 with studded Hakkapelittas in winter and she actually went out of her way to thank me after her first drive in the snow with the new snow tires, both were new drivers in the beginning. Every one of my DDs for the last 30 years have worn 4 snows and never had a problem. They also have driven past many a pickup or SUV off the road or smashed in slippery winter conditions.
Phil - Good point regarding limited slip on snow/ice covered roads/highways. Requires a knack for feathering the pedal. Doesn't take much for the *** end to break away.
Thank you Norm, and yes precisely. As a heads up it should not be forgotten. Everybody is not Mario Andretti. There is a learning curve for those unfamiliar with it.
Originally Posted by CutlassMarc
That is more a tire issue, than the limited slip in the snow.
Originally Posted by Vintage Chief
Disagree
And you would be correct Norm.
Originally Posted by 69CSHC
Meanwhile my 67 open rear Cutlass drove dead straight in worse conditions, even when heavy footed...
Had both cars at the same time, both had the same tires. Limited slip is more work with the same tires. Limited slip caused the issue. I had to alter my driving pattern to make it work.
Limited slip has been around for 90 years. Millions knew and know that the rear kicks out under certain conditions. This is not an out of the blue phenomena. Burnouts emulate what happens when traction is momentarily lost. Posi/limited slip kicks the rear end out, peg legs/open rears stay straight. The phrase "Mustangs doing Mustang things" did not materialize from thin air.
Originally Posted by Koda
Not everyone runs winter tires in the winter.
Exactly.
I live in 4 season territory, and good all season tires are more than adequate till you have a limited slip.
It's an issue... One way or the other you need to counteract limited slips inherent weakness, loss of lateral stability under certain conditions.
Here in Michigan everyone has AWD/4WD, I consider four wheel STOP more important, snow tires are the only thing that will give you that on snow and ice, regardless of how many wheels are driving, I've been using Blizzaks for 30 plus years, usually get 4-6 years of safe winter driving out of them, extends the use of the regular tires also, cheaper in the long run.
