How big of a problem is this?
 

so i have seen a slight decrease in power, especially in 5th gear. I thought my rear cvs were going but am starting to think otherwise. i seem to slip a bit and get a "clunk" in the rear when the gears catch. Possibly transaxle or something.
Suggestions on how to narrow down this issue? This is my only daily driver so i will need to line up parts or info on re-bilding

4th gear on a slight inclide, hold down the brake and give it gas at the same time. If the revs go up and the speed dosent then your clutch is slipping. You can get the same effect on the highway in 5th gear..hold brake and give it throttle. Clutch slippage is going to be worse in the higher gears. The slip, then clunk you are feeling are probably the 'limp home' tabs on the torque tube. The car will still move, however that clunk of the tabs locking is going to put alot of undue stress on your ring and pinion.

well clutch seems fine. alot of slacl coming from the rear

CV Bolts?
 

check that the CV bolts are good and tight. They sometimes loosen up.
Check lugnuts as well.

lol, all are good. im going to replace the CV's this week and start there.

After going fr a ride tonight i can feel/hear a growling or dry bearing sound in rear axles. also forgot to mention the shifter vibrates at 3000rpm to 3800rpm.

You don't have a rubber center clutch do ya?

When they go they start to "clunk." Nothing like a CV though.

JR

Last time you changed the tranny fluid?

Expensive game of darts. Don't just throw parts at it. Just take some stuff apart to find out WHAT is wrong. Guessing is expensive.

When was the clutch replaced? Don't rule that out, as it normal to slip in the upper gears do to more clamping force needed to turn the taller gear. If you still think it's something else.
First change the fluid, that'll let you have some idea if it's internal or not. Like teeth on the R/P gears. Make sure no metal. Refill, test drive.

2ND get the proper 16pt allen key, remove and inspect the joints. Any break in the cages will be obvious.

Growling noise, = bad bearing.

the output bearing (right behind the c.v. cup on the Transaxle (T/A) on the exhaust side go's bad due to the close routing of the exhaust system. Not saying thats it but just an example.

Couldn't really figure out from your descriptions what exactly is going on, but, usually on 944's there is multiple issues. The problem is the cheap buying price for the car, but still somewhat expensive replacement parts. Previous owners of these cars have been known to skip important maintenance.