I know I'm probably asking a dumb question, but I'm in the process of building a Spec7 Race Car and it just came up. I have an 85 GSL with Drum brakes and normal (non limited slip) Diff. Do I have to spend the $650 bucks to buy a used, but complete 10" disc brake rear end with limited slip, or can I fit the 10" disc brakes and the limited slip to my present assembly? Logic says all I need are the limited slip and the brake parts, but since when does logic have anything to do with racing!

Thanks much,

John

 

Try the racing section.

 

An '85 GSL should have disks and LSD factory. Who knows what you have under there.
The third members are easily swapped to you pay attention to years: (disclaimer: This info is from memory and I haven't owned a FB in years.)
79-82 has a small axles and small driveshaft flange
83 small axles and larger driveshaft flange
84-85 have larger axles and the larger flange (most desirable)
Drums to disk is not a bolt in, the axle tubes are different.
The easy way is to swap the entire axle for a disk/LSD. $650 for the assembly is way out of line. $200 is more the norm.
Be sure to get the correct master cly and prop valve.