Hey Guys, I have a 68 Olds Cutlass S, with a 350 engine and a jetaway auto transmission. on the floor consul. I am going to swap it with a 350 trans. What are the olds years that would be best for this swap or should I buy a new on and if so what would be the best one. What would be the best torque converter for this swap or do I need to change it. Both the trans and the converter are original. There is a little slip in the trans sometimes. Thanks for the help.

 

It is the easiest and best bang for the buck swap out there. Any BOP short tail TH350 from 69-80 is fine. Pontiac Olds or Buick powered Intermediate A/G body or some X / F body. Assuming stock engine , stock stall is ok but a little Hughes 12" GM20 stall (2000) is not bad if your in there. If your planning a cam swap maybe go ahead and get the GM25 2500 or equivalent from another brand. There are a lot of them still out there for pretty cheap since so many are overdrive crazy these days. I am running a used rebuilt one I got off craigslist that was out of a early 70's firebird and put it in my 70 Cutlass wagon and it is holding up well to my 455 so far. Had lots of cars years past and did the same ST300 swap in a 68 LeMans. I have 4 of them now kind of stocking up on them. Acceleration is greatly improved with a 2.52 low gear versus a 1.76 and no mods required except if you want manual control of low gear and you may need to fiddle with adjustment some. sometime you can just browse a junk yard and find a dirty engine in a car with a clean (rebuilt) trans. Rebuilds used to be really cheap but now may run ya $500 used to pay $150 LOL

 

You'll need a kick down cable also.

 

True, I forgot to mention that but honestly we hardly ever used them and had em cut off. Just manual control when we wanted to.

Here is what is likely a good one sorta near you

https://columbus.craigslist.org/pts/5359639697.html

 

With the console shifter, you could swap the 2 speed for a 3 speed setup fairly easily:

http://www.shiftworks.com/cutlas67-72.htm

Use your factory-installed automatic floor shifter with a newer 3-speed (TH350 or TH400) Transmission. The conversion includes a new laser cut and hardened detent for proper stops and gear selection, a new matching transmission shift lever, cable pan bracket, console lens indicator, all necessary hardware, cable, and instructions.

 

thanks guys that is just what I wanted to know. you seam to have covered everything, even the link for the Kit. sometime you guys amaze me. the help was spot on.

 

Good luck, let us know how it goes.

 

You'll be very happy. I did the same swap in my '64 Cutlass (except my Jetaway was a switch-pitch) some years ago with great results.

Had to re-train myself to keep from lighting the tires every time I took off from a dig!

 

I did exactly this swap decades ago on a 1968 F-85. The only trick is that since the TH350 didn't exist in 1968, the hole for the kickdown cable isn't punched in the firewall. I had to cut a hole below the throttle cable hole. 1969-72 cars have the hole punched and a small cap installed over it if the car didn't come with a TH350 from the factory. Of course, you also need to swap the accelerator pedal to the correct TH350 pedal that has the provision for the second cable.

 

Or, he could go with an aftermarket setup with a bracket that hooks the kick down cable to the carb.

 

Yes and or he could get a TH350 off a pontiac that already has the cable that goes to the carb linkage and just home FAB a simple or existing bracket to attach manifold to but the main thing is the detent cable doesnt not have to be hooked up to get it going and enjoy the immediate benefits. it can be just tied off at the firewall tucked behind bell housing till it needs to be hooked up. I wouldnt let this delay the the swap if he gets a reading to go transmission. Especially since most TH350 governers only downshift and upshift to like 4200 rpm or something it at WOT

 

Back in the old days I had one of my first , actually my second car a 68 Lemans. It had a tired 350 2 barrel (9:1) , two speed , 2.78 gear and single exhaust. It was gutless and couldn't do a burnout because of lack of gear mainly and could go 80 mph in first without even over revving engine. In short order just doing a TH350 first , then dual exhaust and then a 3.23 posi and finally a four barrel Qjet swap, the changes were INCREDIBLE! it was like 125 hp nitrous shot. Tire frying and maybe 14 second ish performance where as before maybe 17 or 18 in the quarter. bang for the buck hell yeah

 

thanks for the info guys, I have emailed the Columbus guy about the trans he has for sale but have yet to get a return. there don't seam to be a lot of them around in my area here. only other one I've found is in Indianapolis IN, no return on that one either.

 

I did this swap on my '69 but she was originally a TH350 car. For some unknown reason a PO had dropped in a ST-300 (Jetaway) from a '68 Buick in place of the TH350. I spent a fair amount of time with the assembly manual to figure out what was/wasn't present. In my case most of the items were present but I was missing the cable retainer bracket that bolts to the bottom of the pan on the TH350. The Jetaway/ST300 bracket is different and won't fit the TH350 pan but repop brackets are available. I didn't need the complete kit so I just bought the missing pieces.
My trans is from a V8 '69 A body Poncho with a smattering of parts from a '72 Cutlass. I found 2 cores (one on Craigslist, one in the junkyard) and took the usable parts from both to make one. I paid $50 for the Craigslist trans and $80 for the junkyard trans so they're out there. I built a jig to mount a BOP TH350 to my engine stand. I can provide pics/dimensions if you need them.

 

Give him a call at the number he shared, he said he doesn't do text so probably a email slackers too.

 

I have responded to his ad but no reply (2 times) I have tried to call but no answer. I will try again on Sunday. thanks for info.

 

Don't know if you'd be interested in this one as its in SC.
https://classicoldsmobile.com/forums...shift-kit.html

 

I just got back from looking at the transmission that Gearman69 referred to in Columbus but am confused about it. It looks like a olds trans but the numbers ?????. on the very top of the bell housing between the top bolt holes is a large 2 C. down the left side from there on the bell housing is the number 8640 3 99 FD that I m assuming is the casting number. NOW on the left side just above the pan stamped on pad is the number 48X153971. there are no letters at the start of that number or anywhere else on that transmission. there is a large number 7 on the top middle of body of the transmission.????????????help.

 

I think you need more question marks...

The only numbers that matter are the VIN derivative and the code from the metal tag on the side of the trans. You didn't provide the code from the tag, but the 48X153971 VIN derivative tells us the following:

4 = Buick Division
8 = 1978 model year
X = Fairfax, KS assembly plant
153971 = sequential build number of the car it came in

I'm not sure what cars Fairfax was building in the 1978 model year, but in earlier years it was solely full size cars. I'm guessing this trans came out of a 1978 Buick LeSabre or Electra.

 

thanks for the info joe. not enough question marks joe. next question is will it swap to my 68 cutlass and what would be the problems.

 

If it's a short tail TH350, it's a bolt-in.

 

I forgot to say on last post joe, there is not a tag on the trans. the numbers I gave you are all that I found. I don't know how to send photo's or I would send one. yes it is a short shaft.

 

It said it is out of 71 Cutlass which would be 100 percent correct. You probably are looking at random casting numbers. It's the right tranny. BOP bell, short tail 350 bolts in nothing easier.

 

he said it was a 71 cutlass trans gearman69 but joe was able to run what numbers I found and said it was a 78 Buick trans. it looks just like the photo you posted.

 

No problem, same tranny.

 

Any short-tail BOP TH350 is a simple bolt-in. If 48X153971 really is the VIN derivative from that trans, it's a 1978 Buick. Dimensionally and functionally it's identical to a 1971 Cutlass trans.

 

thank all of you guys. joe and gearman69 just told me what I was looking for. Going back to Columbus tomorrow. thanks.

 

Did you get it ? We want a burn out vid after the swap Merry Christmas

 

Yes Gearman69, I went back to Columbus and got the tranny. I have also ordered the kit from shiftworks. I may not get it in right away. I don't want to put in a trans with 120K miles on it so I am going to have a rebuild on it before I do. Sorry about the delay getting back to you, It has been a really, really bad time for me right now. Thanks or all the help.

 

Glad you got it, hope things get better for you soon. I expected the rebuild no biggie.