Some odd noises
 

Hi all, I'm noticing some odd noises and can't seem to find another thread on the site that matches up with my symptoms. Car is an 89 gtus.

First noise:
A fairly loud ( I can hear it over my 2.5" exhaust without a cat) steady clunking noise that only happens when I accelerate on the highway in 5th gear, sound seems to go away after about 3500 rpms, and is not present when just cruising. I know I have a bad front wheel bearing, which makes a sound similar to this when I hit bumps on the freeway. Possibly a bad ujoint?

Second noise:
Pretty recent, a grinding noise when I am coming to a stop, sounds more like a bearing growl than bad brakes to me, could this also be my bad wheel bearing?

Thanks for any input anyone can provide.
PS, I checked my rear diff fluid and trans fluid about a week ago, both looked good

personal circumstances aside, it might be a good idea to stop driving the car until these things get resolved. neither issue sounds like a good (safe) outcome if they go from breaking to broke.

start with checking ALL the bearings since you said you've already confirmed that one is bad.

for the clunking noise, do you feel anything in the shifter when you're experiencing it? you should probably jack the car up and check all the driveline components for extra movements that shouldn't be there. check everything from the engine back - mounts, bushings, joints, etc. maybe remove the driveshaft altogeher and check it for balance.

for the braking noise, did you recently change brake pads? any vibrations with it? check all four corners for any loose components.

I'll have to feel the shifter next time it happens, but other than that, it shifts fine in all gears, no grinding, not hard to get in or out of gear, etc.
I changed brake pads about 2 years ago, but did not replace rotors with them.

The drive shaft was fine when it was coupled to the previous transmission, but something could have happened to it while it was sitting in my garage or during my install, so I'll check that out. I do notice some clutch chatter/ clunking noise when I have it revved up in first gear and press the clutch pedal really fast. Not sure why that happens, its a brand new exedy throwout bearing and the flywheel didn't look bad when I had the trans off. Not sure if that would be related to my other noises.

Just an update several months late in case anyone else has a similar problem. The noise was the transmission's large rear mount. The threads were damaged so the nut could not be tightened all the way, so it would bounce and "slap" the underside of the car when driving at certain rpms. The mount had about .25" of play in it. I made a thick washer out of some plate steel laying around and a hole saw so it would fit properly in the rubber insulator under the trans mounting nut and stud, which took up enough play to tighten the main nut properly, and the noise went away.