Differential interchange

[Snag]

I'm re-gearing my '86 GMC pickup , and want to go with a limited slip
unit . It's a stock 2.73:1 8.5" 10 bolt right now , and there seems to
be some confusion as to what will fit .
As far as I can determine any 8.5" 10 bolt will fit my differential
housing , the only difference being the axle spline count . Everything
I've found says I should have 28 splines in the 1986 .
Anybody here that can verify ? I'm in no particular hurry , it looks
like winter arrived here with a vengeance .

[MummyChunk]

Post by Snag
I'm re-gearing my '86 GMC pickup , and want to go with a limite

slip

Post by Snag
unit . It's a stock 2.73:1 8.5" 10 bolt right now , and ther

seems to

Post by Snag
be some confusion as to what will fit
As far as I can determine any 8.5" 10 bolt will fit m

differential

Post by Snag
housing , the only difference being the axle spline count

Everything

Post by Snag
I've found says I should have 28 splines in the 1986
Anybody here that can verify ? I'm in no particular hurry , i

looks

Post by Snag
like winter arrived here with a vengeance
--
Sna
Si Vis Pacem Para Bellu

The 8.5" 10 bolt was used i
many different models by every GM division, with the exception o
Cadillac, during the 1970s and 1980s. The carriers and gears ar
easily interchangeable, and the original gear ratios range from 2.41:
to 4.10:1. The 8.5" 10 bolt has two types of axles: 28 spline an
30 spline. The 28 spline axles were used until 1988, and the 30 splin
axles were used from 1989 and up. Therefore, if your '86 GMC picku
has a stock 8.5" 10 bolt with 2.73:1 ratio, it should have 2
splines. You can verify this by counting the splines on the axle shaf
or by checking the axle code on the right lower cover bolt

If you want to go with a limited slip unit, you have several options
You can either find a Positraction carrier from another 8.5" 1
bolt with 28 splines, or you can upgrade to a 30 spline carrier an
axles. You can also use an aftermarket locker, such as an Eato
E-Locker, which can switch between an open carrier and a fully locke
differential. However, you will need a special bearing to use a 3
spline carrier or locker in your 8.5" housing. You can als
change the gear ratio if you want, as long as it is above 2.73:1. Yo
will need to adjust the pinion depth and backlash accordingly, and us
new bearings and seals


This is a response to the post seen at
http://www.jlaforums.com/viewtopic.php?p=658725873#65872587