I recently found a gsl in a junkyard with the rear end and need to know if I need to get the driveshaft as well in order to swap it into my '80. I took down the vin and was wondering if anyone happens to know when the switch was made to the larger axles. They say it is an '83 and from what I read, that means it could have either. I also took an awful camera phone picture that I doubt will do any good but I will attach it anyway. Thanks for any information.
The vin is: JM1FB3317D0736353

 

Sorry for the extremely large picture, I should have just left it as an attachment.

 

Simple way to tell if the flange is the large or small. 4 threaded holes = small. 4 non threaded holes = large.
The one in that blurry as hell pic, is a large flange, you will need the driveshaft. And the brake cables (rear section) along with the rubber flex hose from body to chassis.


For the record, all 83's had the large driveshaft flange, and small axles, according to parts microfiche's.

 

Wow, I'm impressed you could tell anything from that picture. Thanks for the information. That's what I need to know.

 

It wasn't easy on the eyes, but those bolts/nuts at the driveshaft connection are still rather noticable. All large flange diff/DS combo's have bolts and nuts, while the smaller one has just bolts.

 

Dont you also need the Proportioning Valve from the donor car also?

 

The PV is a good idea, however, 81-82 used the same PV rather it had drums or disc rear brakes.

 

So if you have a 83-85 then you need the PV

 

In theory, you need a PV from a 83-85 disc brake car, along with the matching master cyl. In reality, you can use the PV and MC from a drum brake car, without any real problems. I swapped an 84 GSL rearend into my 83, and didn't swap the MC or PV. I later changed the MC to a disc brake unit, because the old one started leaking. I still haven't got around to swapping the PV, even though I have one from an 85 GSL.
I do not know if the later GSL PV gives more or less rear brake bias, but I assume that is what the difference is. I don't have any problems with brake lockup on either end, even when using the brakes rather hard (autocross).