I've played with mine in the past for quite some time but have learned to live with the loose pedal. The first stop of the day can be worrisome.
The booster input rod has adjustment as well, but I've not been able to move it. There's an important measurement there to get right. The TSRM...
(from my failing memory) Sport Package = non-turbo, headlight squirters, ABS, 4.3 LSD, TEMS. Mine has a manual transmission. I don't know if you could get the Sport Package with an auto trans, but I suspect not.
ABS was still an option in 1988.
Impressive! However, I don't believe it has an LSD, which was for the "Sport Package" in 1988, which I have. It doesn't have the tell-tale headlight nozzles. This one probably also does not have ABS.
And, the head gasket is just waiting to go.
The heater box definitely comes out without breaking into the A/C, but it needs to be separated from the A/C box. Once the dash is out, the rest is easy. You can leave in the seats and carpet.
As I recall, the floor heater duct sits on top of the transmission hump and points down on both sides...
There's a thread on rebuilding: http://www.supramania.com/forum/threads/how-to-rebuild-the-mk3-rear-differential.203766/
Good stuff there.
Driftmotion sells a rebuild kit, which I recommend, as it's a good deal.
And, do the solid pinion spacer thing.
You can temporarily demagnetize a magnet by heating it up over its Curie temperature, but it will remagnetize after it cools down. Mechanical shock also will reduce the magnetization, but not get rid of all of it. Neither is really possible here.