i have an 86 disk brake rearend,10 bolt. since my 87 has drums in the rear,i want to install a 3.42 posi in the disk brake rear and install it on my car. my dad looked up the posi traction unit and said the prices for the 86 and 87 were dif. (the 86 was more expensive) whats the deal? can i just swap the disks onto my drum rear now and install the posi and gears on the 87 instead? whats the best way to go?

any help is appreciated

 

if your 86 has discs then its a 9 bolt borg warner diff
and your 87 is a 10 bolt
go to 9bolt.com to look up parts for it they are expensive

 

But if it's a 9 bolt it's strong as hell and you don't want to get rid of it.

 

I have an 86 IROC and Disc brakes and I have a 10 bolt.

 

Depends on the Gear ratio on the 86 & 87. If both are 10-bolts and are the same series carrier (2 vs 3) you should have no problem. Rpo G80 Limited Slip & J65 Rear Disc brake would cause the difference in price for the 86. Also if both are 10-bolts you can swap the Disc's for the rear drums. Advice make sure both rears are 10-bolts before swapping parts.