Adjustable suspension = GXL with auto adjust suspension (AAS)
Hard Suspension = 5 Bolt (I think)

 

Getting rebuilt calipers is a good idea, as the pistons on yours might be corroded and could cause problems or they might not be usable.

The suspension question is basically trying to determine if you need the narrow solid rotor or the wider vented rotor rear calipers.

 

Not exactly right.

The following had 4 piston front brakes with vented rear brakes:
86-87 Sport
86-90 GXL
87-91 Turbo
88 GTU
88-92 Convertible
89-90 GTUs
91 Coupe with A package

The following had single piston front brakes and solid (not vented) rear rotors:
86-87 Base
86-87 Luxury (GX in Canada)
87.5-88 SE (GX in Canda)
89-90 GTU
91 Coupes without the A package.

When the auto parts store asks if the car has the heavy duty suspension, the 4 piston models are what they really are referring too as most of the parts books refer to the 4 piston systems as heavy duty.

 

Icemark,
A friend of mine has a GXL with a solid rear disk, are you sure that they had a vented rear disk?

 

A TurboII should already have the 4-piston calipers, no?

 

Yes it does, I couldn't remember. I said in an earlier post that the car sat still for a few years and I thought from working on the brakes from a few years ago it had two piston calipers. Since then I have bled the system and put in a master cylinder brace. They are 4 cylinder cals on the front.

 

Yep, they all had single piston vented rears with 4 piston fronts.

What makes him think it is a GXL? year ?

 

If I recall correctly it was a s4, and it had AAS.

 

someone put the wrong rear end on it then.

Because it came from the factory with vented front and rear brake rotors