First, welcome to the CAC "iraqvetmac" and thanks for serving.
Lke to make a couple of points.
First I totally agree with Elaine.....
At that asking price of $23.5k, the owner is clearly using "Grand Sport" as a selling tool. That car is WAY overpriced...period!! Should be somewhere in the vicinity of $15k, if that high.
23,500 is way high and even 15K is questionable, but I think you got the message on that. Clearly some of these folks are either not real anxious to sell, haven't a clue as to selling prices or are just looking for some fool with too much money and a hard on for a 96.
The 131,000-mile LT4 convertible might be an adventure. With that high miles, the thing will probably be full of squeaks and rattles.
As for the clutch and transmission discussed early in the thread...the statement was made that ZF S6-40s can be noisy because they have straight cut gears. What B.S! ZF six-speeds have helical-cut gears just like every other modern manual transmission. I don't know where this bad information comes from.
In good condition, the flywheel trans and clutch in 96 should make a modest amount of gear rattle in neutral and should growl a little in first/second gears.
Now if there are problems they can be one of several..
1) With that high mileage, the dual mass flywheel could be faulty. A bad thing as dual mass wheels are no longer available. Your only choice is to convert to a standard wheel and accept the increased noise that brings. A sign of a failed dual mass wheel, is a rattle, after you turn the engine off just as the rotating assembly comes to a halt. Now, if the flywheel's secondary mass is slightly warped but the dual mass system otherwise is working, they can be machined but there are very few machine shops who understand how to set-up and do that. If that's your situation, look for a machine shop that already knows how to do dual-mass wheels used in BMWs and other European cars.
2) Typical noises made by failed clutch release bearing or pilot bearing.
3) Loud transmission whine or howl can indicate a problematic trans but also can be indicative of the wrong lubricant.
4) Increased gear rattle from the trans can be a sign of a bad dual mass wheel.
Repair of those items might run you that 1500 bucks you cited earlier....or more.
Good luck with your continued search.