1987 Caprice rear end
 

i want to change gears in my rear end but i dont know what inch rear end i have in my 87 caprice.

7.5" 10 Bolt.

http://novaresource.org/axle.htm has pics that will help you see if it's an 8.5" or a 7.5" rear.

if it has 9c6 or 9c1 on the sticker glue to the trunk lid then it will be 8.5"

also would have larger brakes and 5 on 5" wheel bolt pattern like the trucks and station wagons

what size motor you have?if it's not a 350ci more than likely it's a 10 bolt 7.5.

Okay Thanks For The Good Replies, Was A Big Help.

Learn how to tell the difference between 7.5" and 8.5". GM didn't seem to have any set rules on what car/engine combo got what rear end or what wheel bolt pattern. I suspect a hi-po model would get the 8.5" for sure, but some of the mid-sized turbo Buicks from the '80s got 7.5" units, so who knows for sure.

Last year I junked a couple of Buicks that illustrate my point. One was a big old '82 Park Avenue that had a 307 Olds motor, a 7.5" rear end, and the 5-on-5" wheel bolt pattern. The other was a slightly smaller '84 LeSabre, also with a 307, but it had an 8.5" rear and the 5-on-4.75" bolt pattern.

caprice rear end
 

I changed my 91 caprice from the standard 2.56 to a 3.42 eaton posi, the effect was great, it jumped from 70 to 90 mph and from a stop I could turn the car without moving it forward,Lots of fun too. In that year the 3.42 was put on the police cars, in 94 I think the 3.23 was the highest ratio offered.

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