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1987 Caprice rear end

14K views 8 replies 7 participants last post by  Crosley 
#1 ·
i want to change gears in my rear end but i dont know what inch rear end i have in my 87 caprice.
 
#7 ·
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.
 
#8 ·
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.
 
#9 ·
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.
87box has not logged in since 10-2009 .... read dates on threads as you search in Hotrodders. The members may have left the forums
 
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