I've read that the brake-line connections can't interchange between '79/'80. How about between '80-'85?? Also what about the entire rear-end? I've seen a vid on youtube in which it shows that the '79 rear-end is mounted slightly different than an '81+...but does the '80 rear-end mount the same as '79 or '81+...?? Also when interchanging rear-ends (I wanna swap in a '83 GSL rear) will I also need the drive shaft from the GSL car??? (It seems logical that the larger, LSD equip'd 3rd-member could be longer...)

 

79-80 lines are the same.
79-80 lines/hardware NOT interchangeable to FB 81+ wo swapping some hardware
81+ rear ends no problem for SA but you need to get an adapter line for the forward (ie front section of rear lines) that allows the FB lines to attach to SA system. mazdatrix and others sell these, usually as a stainless steel line.

I know there are "conditions" for swapping drive shafts but will let others speak to this.

Stu Aull
80 GS
Alaska

 

The driveshaft length is the same between GSL and non GSL rear ends, what you need to watch for is the size of the driveshaft flange on the rear end. 79-82 have the small flange and 83-85 have the large, so just match the driveshaft to the rear end you are swapping in.

Like Stu said, you will need an adapter for the hardline coming from the body. At one point Re-speed made a custom brake hose that did this, not sure if they still do or not.

Also, what vid on youtube are you talking about? All SA/FB rear ends use the same 4 link and watts link locations and can be bolted into any SA/FB body.

 

On the 82/83 flange change; I've often wondered why people don't just swap flanges? Based on the parts lists, it looks like all the other parts involved - - pinion shaft, seals, etc - - seem to be the same.

Is it because removing the flange involves upsetting the rear-end setup, or is there another, deeper issue I'm not seeing?

 

^No, you got it, we just don't want to go through the hassle of setting up the rear end properly after changing the flange lol

 

another thing to note when goin from one flange to the other is how its attached to the pinion. 79-82 pinion flange is threaded, so bolts go strait through the drive shaft flange and thread into the pinion, while the 83-85 pinion flange is an untapped hole, requiring 4 slightly longer bolts that go through the 2 flanges and nuts on the back side to tighten the two together.


its a minor difference that most people can deal with by digging through a bucket of random bolts they've collected over the years, but its still nice to not be suprised when you go to install everything

 

That's actually one of the easier ways to tag a range of years onto a diff.

 

To go with the original post I also have a wrecked 84 GSL with lsd that I'm going to stuff under my SA. With the hardware add-on's I'll just need the driveshaft and rear end out of the GSL and I'll be set? The nut's for the flange are still there and all. lol

 

^You will need to do something about the brake lines. The 81 and newer use M10x1.00 while the 80 and older uses m10x1.25 (which is very uncommon) so you will need to either change the flare nut on the body hardline (easy to do, but requires a flaring tool) or contact re-speed and see if they still have the custom brake hose with the SA thread on one side and the FB thread on the other side.
Besides that, yes its all a bolt on deal.