1974 el camino rear end questions

Ok when i bought this car, the guy who sold it to me said he put 373 gears in this thing. It is a 10 bolt Gm coorporate rearend per the dog ears on the bottom. The problem is its "howling" when you drive it. I really haven't had any problems with rear ends throughout my time with cars, and I'm a boat mechanic so the rear end usually stay in good shape on those...lol....my questions are:

1. What generally causes this? Gears? Shims? Bearings?

2. What parts are interchangable throughout the years? Can i take the guts out of one? If so what?

3. Would it be a better idea to but a different rearend per this site or craigslist or junkyard and just put it in there instead of messing with the one i have? If so, what reaends from other cars fit?

4. Should I go posi? Can i go posi with what I have? How can i tell if what i hav is posi?

any help would be great....I really love this site..........thanks in advance

I'll try to answer these questions as best as I can.

1. Probably wasn't set in there correctly. Get some gear marker & verify this. Maybe you just have a wheel bearing that needs replaced though?

2. It's the 8.5 rear. All 1973-77 A bodies used this axle & interchange. Some were bolt on & some were C-clip style though so that's the only thing to worry about. Gears can also be found under some 77-96 Caprices, 80's model 442, Monte SS, & Buick GN, most 1/2 ton pickup trucks made from the 70's on up, & I believe that even vans got this rear axle.

3. Complete rear axles from any 73-77 A body or any 77-96 B body will swap in directly. Cop versions sometimes came with 3.42 gears, most others had highway gears. Some early A bodies had 3.31 gears as well & you might get lucky enough to find one with a posi. Whether or not you want to mess with gear swapping or rear axle swapping is your choice, but a rear axle isn't too expensive & is fairly straight forward to swap out. Four bolts, the E brake, & the brake lines.

4. I always recommend posi or some type of limited slip, but that's me. See 2 & 3 for answers to the posi question. Stay away from the Gov-lock posi in trucks as they aren't very reliable. I found this out first hand with a relatively stock truck. You can put limited slip in any 8.5 no matter what it originally had. Best way to tell if you have posi is to pop the cover & look. Not like it harms anything to change the axle grease. An old standby that works most times is to jack the car up & see if both wheels spin the same direction, but sometimes even with posi they will turn opposite from what I'm told.

There are two differant size carriers. One is for 2.55 gears and lower ((2 series carrier)) and ((3 series carrier)) is for 2.72 gears and up. JB

Since the 73-77 cars only ranged from 2.56-3.42 does that mean they all used the same carrier then? I never knew that 8.5's even had two different carriers, I thought it was just the 8.2 10 bolts. Thanks JB.

The 2.56 was a smaller carrier than ther other ratios. Hey, I only missed it by one number,lol. JB

Rago wrote:Since the 73-77 cars only ranged from 2.56-3.42 does that mean they all used the same carrier then? I never knew that 8.5's even had two different carriers, I thought it was just the 8.2 10 bolts. Thanks JB.

I actually added that Rago and yes there are two diff carriers

You missed the other number by one too JB, it's a 2.73. I have one of those laying around here if anyone needs one.

Posi and what gears ??

what are the prices on those things over there? I checked ebay once and they were around 1000 bucks which seems a lot to me...

The one I have is an open 2.73, removed from my '75 . Code on the axle housing is
ACC 141 1

I've actually got three complete rears that would work. Still debating on which one to use.

2.73 open
3.08 posi
3.42 open

I wish I had that 3.08 Posi to use as a spare in case I tear out my 3.47 posi. JB

Those 8.5 rears will take a lot of punishment though. Some guys run big blocks with those. Only thing I noticed is that the axle housing wears quite a bit where the OD of the outer axle bearings run, after beating on it for a few years. Then the housing needs the aftermarket C-clip eliminators with the ball bearings, to save the housing.

I have Moser 31 spline axles twisting 3.42 posi gears (or is it 3.47, always forget that last number) behind a 540 Dart Big M. I have not abused the rear TOO much, but so far it has held up just fine. Maybe this summer I might get a chance to put on my slicks and give it a real test on the strip. Anyone wanna drive it for me? I'm not a good driver. JB

Those slicks may do a number on that rear!