Well... I finished my brakes and they are 100% - I replaced the front inner/outer bearings and seal - the passenger outer bearing was in very very bad shape - which made me a little scared for the rest of the bearings in the car - 72 convertible - the rear pinion seal is leaking - I’ve read a lot of the posts in this section - It is a 10 bolt - 8.5in - bolt in axle set up - id guess 28 spline and a mild gear ratio (guessing 2.53:1 or what ever as it doesn’t **** and get with a 455) (clutch is slipping but that’s another day) won’t know until I pull the cover - was able to get the plug out with little problem - the diff took almost 2 quarts of gear lube before it started leaking out the hole - the axle seals are not leaking on either end - just the pinion seal - few newbie questions - are the bearings in the rear end packed like front end bearings or does the gear oil lube them? From what I’ve read the axle bearings are pressed in so I’d need a shop with a press to help - how many bearings total in this rear end? (Both axle ends and pinion - are there inners?) I have never messed with a differential before - some friends are telling me I don’t want too - long story short - how big of a job is the pinion seal? (Wondering if I can do it) IF I ran it in the past low on gear lube what should I be looking for / worried about in the rear end - I’m a little hard of hearing and I have a four speed M-21 (I believe) so I hear that Muncie whine when decelerating but haven’t noticed rear end noise (again hard to hear with no top and just wind noise (just recently got the top)

Axle Bearing: Timken Set9
Axle Seal: 712146
Carrier Bearing / Race: LM501349 / LM501314
Pinion Head Bearing / Race: M802048 / M802011
Pinion Tail Bearing / Race: M88048 / M88010
Pinion Seal: 2043

thanks for sharing that! Know any good links on doing the deed?

thanks! Exactly what I was looking for

awesome! Thanks!

thank you for the info!

ive been doing my reading on this one and I think I’m going to pull the whole housing and have it done by someone with experience - going to have it rebuilt - I also believe that’s where my vibration I’ve been chasing is coming from - and I agree - going to add the Posi and up the gears - debating between 3.08s and 3.23s I do want to run it on the highway - about one hour and fifteen minute drive between towns - any advice on ratio? I don’t have to pull wheelies - but don’t want to embarrass myself against modern mini vans etc hehe

thanks - leaning towards 3.23s figure that will “pep” her up a bit to make it more fun and still be able to afford an hours worth of gas on the highway hehe

thanks for the info Jim! I actually do not drive it hard - not saying I don’t want to someday 😜 - i am somewhat hard of hearing but I did not notice any bad sounds coming from the rear end - It does a lot of sitting as I am working hard on getting it up to snuff - I noticed a small stain on the driveway under the rear end recently (have had the car for 18 years - did a lot first couple years - financially fell on my *** for a bit and three years ago got back at it) and have kept my eye on the stain - did some short hops to work etc but nothing major - thinking maybe last summer I added air shocks and raised the *** a bit and after all that sitting the new angle had at the seal and bearings? - anyway the leak is now very bad - I added two bottles of gear lube and it steady streams out the front pinion seal - that and the up down side to side play conserns me - your the expert on these - was actually going to message you for advise - I’m prepared to pull the whole housing - got a $400 to $500 estimate on rebuilding it as is in Grand Rapids mi - but everyone’s telling me to swap gears and add Posi while it’s out (which I am aiming to do) but I am having a hard time finding gears and Posi on line - they either are c - clip axles or they omit info like not telling how many splines etc - I saw your 3.73 rear end but those gears are steeper then I wanna go - looking more towards 3.23s I think? Anyways - I’d like to give you my business if it’s possible logistically? (330) that eastern Ohio area? Thoughts?

I think this is what I want for my 72 olds 8.5 28 spline boot in axle differential - anybody know otherwise?

i was in communication with Jim about this but I think he might be busy - I don’t want to spam him - This Posi is the closest I’ve found so far - amazon says it doesn’t fit my car but Jegs says it does (72-74 cutlass either base or s / 5.7 and 7.5) - I doubt amazon knows - only thing that seems screwy is it says “GM” Not olds specific - and as far as I know my rear end was 71 to 72 only - so nervous that they might think it’s c clip axle as it also says it fits many chevys - I just posted a question to jegs about it - just figured I’d try here as well - I’ll post what they say - thanks!

ok I will try again thanks

thanks for the tip - I will try that

got the rear end done - working on bushings then reassemble - any recommendation for brake in Jim? And what gear oil for this Posi? Also... made a rookie error - praying it’s not crittical but I knicked the inner dog ear with a hack saw cutting the sleeve out - pic attached - let me know how bad 😩

just red to throw a little color in there - also it makes it feel “cleaned up” to me - all black feels like it could still be rusty greasy in the shadows - can barely see it - car will go metallic grey in the big picture - I have the aluminum diff cover that will go on it after the initial break in and I change the gear oil - as far as the nick - it wasn’t bad so I’m not sweating it - i had to hammer pretty good to get the new bushing in - so if it was gonna create a problem I figure it would at that point *shrug*