fiona72

Hey,

There is a post in my local paper for a limited slip rearend and was wondering if it would be something to follow up on. The ad reads:
BIG 10 LIMITED SLIP, 3:42 GEARS, WILL FIT 1970 THRU 1977 MONTE CARLO OR GRAND PRIX. Will this fit into a 72 cutlass? Thanks for your input...

Rickman48

It'll fit, and bolt in, but might be a little wide - measure outside of the drums on yours, and the same on the other for comparison.

redoldsman

i would check this pretty close. I think the rear end changed in 1973. Makes me wonder if they know what they have. If it is a 70-72, it will fit for sure. I am sure somebody else will speak up.

svnt442

Yeah whomever posted this has no clue what fits what. The A-Body changed in 73 and so did the rear axle. They share it with the B-Body from 78-96 I believe.

2blu442

If the price is right you may be able to have the limit slip carrier and gears installed into your housing. But yes, first check to see what it really is as the seller's information sounds sketchy. If you can get some numbers or even a picture of it to post here some of the diff guru's can probably help you key it out and let you know for sure if the whole rear end or even the guts can be installed in your car. John

fiona72

It came out of a 71 Lemans, I guess he was trying to draw a bigger audience with posting the years it would fit. I am going to look at it this afternoon, I believe the numbers I am looking to reference is on the axle tube itself? 2Blu, I might consider changing over the posi unit as well, thanks for the advice.

redoldsman

If it is out of a 71 Lemans you are good to go. It will be a bolt in.

fiona72

The rearend housing from backing plate to backing plate is roughly 54 3/4". The ring gear reads GM 3984831... 12:41 which equated to a 342. I couldn't get the number off the housing without grinding the undercoating off. When I pulled the diff cover off it looked like brand new, still had the grease pen numbers on it. What do you guys think?

2blu442

If the price is reasonable buy it! That gear ratio will be a little hard on gas mileage but way more fun to drive. As redoldsman said it will bolt right up. I'm not an expert with Poncho stuff, so you may need to put in a conversion u-joint or possibly need a different length of driveline. But if needed either of those changes will be relatively straightforward. John

fiona72

Thanks 2Blue,

He is asking 280.00 for it, I was actually looking for a 342 or 373 gear, suprised it was found so close to the house.