[sherman8r]

i have a rear end out of a 1987 caprice police unit with 3:42's huge drums and limited slip that i would like to put in my 1979 caprice aerocoupe. other that the the 5x5 bolt pattern on the 87 are there any other issues i should know about. the 79 has the original one wheel peel 10 bolt and smaller brake drums. is there an axle i can use to get my 5x4&3/4 lug pattern? the axle code from the cop car is 82dg913 i only know the gear ratio from the parts sticker in the trunk

[jimfulco]

Some of the '77-'88 B-body cars had 8.5" rear ends with the 4-3/4" wheel bolt pattern. I had one in a '84 LeSabre that I sold for scrap last spring. I also scrapped a '82 Park Avenue that had a 7.5" rear with the 5" pattern, so be sure of what you have. Either size rear end could be had with either bolt pattern. If you're lucky enough to have an 8.5", your current axles should work in the new rear, assuming it's also an 8.5".

Also, watch out for axle spline count on 8.5" rears. Anything after '88 will have 30-spline axles, whereas '88 and older axles had 28 splines. Some of the later rears will bolt into the older cars, and yours might have been changed by a previous owner, so again, be sure of what you have.

One more thing, watch out for the infamous Gov-Lock "limited-slip" unit. Avoid it like the plague if you intend any kind of heavy-footed driving. Here's a pic:

[sherman8r]

thanks,thats good info and news for me. we found this car at u pull it wrecking yard up the street from my house and looked up the numbers, found 3:42 limited slip. we looked under the car and the diff cover had a tag that says "use limited slip diff lube only" so i turned one wheel and they both went the same way although they were hard as hell to move. is that normal? took off the cover and spotted the springs and called it good.They also have lots of other caprice,pontiacs and buiks to choose from for axles as well, so im stoked. Thanks again

[SSedan64]

7.5" & 8.5" diff ID.>> http://dyeager535.topcities.com/diffid.html

[joe_padavano]

If you can find axle shafts with the right bolt pattern, great, but it might be easier to just have the existing axle shafts drilled for the 5 x 4.75" bolt pattern. The only other problem will be the brake drums. The 87 axle has the 11" x 2" drums. The only 11" x 2" drums with the 5 x 4.75" bolt circle were the ones used on the 73-77 GM A-body cars. You can still get new replacements from NAPA.

[curtis73]

Or go back to that junkyard and find a 94-97 B body with rear discs and swap them over. Still 5x5 pattern, but with the crazy number of identical steel wheels out there with different patterns, no one will notice but you.

I also don't share the same apocalyptic view of the Gov Lock as others do. Don't take them drag racing, but for the street they are a great posi. Fully-open operation with high-bias lockup when you need it. Mine has 137k on it behind a caddy 500 and hasn't missed a lick.

[sherman8r]

i just noticed that the year is 89 not 87. hope it still fits, guess i will have to do custom axles

[joe_padavano]

Originally Posted by sherman8r

i just noticed that the year is 89 not 87. hope it still fits, guess i will have to do custom axles

All 77-96 B-body rear axles (except wagons) are bolt-in replacements. The wagons use a wider rear axle and different control arms. This was done to allow a 4x8 sheet of plywood to fit flat on the floor between the inner wheelhousings.

[sherman8r]

nice, thanks for the info