Is the driveline in the 89 GTUs the same as in the TII? i.e. trans, rear end, halfshafts...

 

No. It's all NA stuff.

 

The only thing "heavy duty" shared between the Turbo II & GTU-S is the suspension, rims, & brakes.

 

yeah, but that is not really accurate to call out; as all the S5 coupe models (except the GXL) used the same springs and shocks and the GTUs used the same stabilizer bars as the rest of the non-turbo coupes.

And all but the S5 base model used the same 4 piston front brakes with vented rear rotors found on the Turbos and GTUs model.

 

did the 88 GTU have the turbo drivetrain? i was thinking it did.

 

Nope. That's a common myth... I used to think so too.

 

thought it had the lsd? well, turbos had viscous lsd, and n/a's had clutch type lsd's

 

wrong....

S4 vehicles that came with LSD had Clutch type LSD's

S5's that had LSD had Viscous type LSD's...

It had nothing to do with N/A vs TII, although TII rear ends are larger and have a different bolt pattern to the driveshaft.

 

No NA cars had the turbo drivetrain.