78 Vette Diff problem??? help before mechanic gets more hard earned money

[78vette]

Hi guys,
Hoping someone out there can help me with a mechanical problem im having with my 78 vette. First off the car has 29k original miles and is in basically survivor condition. When i purchased the car a few years ago all the seals had gone from sitting for so long. Seals were replaced. Couple thousand miles later...maybe just 1000 miles later actually and in a different state and i noticed rear end noise, clicking / clunking around corners etc.
Took the car to local mechanic and he advised it was my rear left hub....with only 29k miles i didnt really believe him so took the car back and jumped onto he net, i found that my year vette needs a posi trac additive placed in the vette when doing an oil change...thinking back to when the seals were changed i had a strong belief they didnt add the extra additive.
Flushed diff oil, a lot of metal particles in the oil...almost glitter , drove for 50 miles and now the real problem has begun!
I believe i need a new clutch pack as the same "wobbly" feeling from the rear and squeaky brakes are back...but coupled with that is a problem when i put my foot flat to the floor, when im stationary...or even driving now i believe but i dont have enough balls to make the noise happen while driving...basically i put my foot on the accelerator ...high revs and i hear the worst sound on earth...i believe coming from the rear, the car also doesnt go anywhere just a real loud noise like my car had driven over a high bit in the road and was scratching all the metal underneath etc. If i take off slow and treat her nice then its ok but it just feels like im babying the thing and its so close to just dying or making the noise again.

Is this due to the damaged clutch pack? im not the most mechanically minded but im thinking maybe whatever goes from the engine to the diff may be damaged as well? some sort of shaft i think it is? anyone have any ideas before i take it to another mechanic to drain my bank balance.
Thanks
SMC

[c4c5specialist]

HI there,

The key is WHEN the noise occurs.

Does it only happen on turns?? Does it happen when going straight??

Honestly, usually I will install a chassis ears listening device and determine where the noise is coming from.

The noises can be coming from the differential, bearings or simply the parking brake shoes.

Accurate assessment of the situation is critical.

Allthebest, c4c5

[78vette]

Thanks, i will try and source out a mechanic with one of these listening devices. The noise will happen either going straight or on a turn i believe. Previously before i realized the last mechic didnt put the posi trac additive in it was only happening on turns...but previously i could always put my foot down and never have the problem i am having now with a horrible sound and the car barely moving. Now i did just get all new belts put on, the belts that were there were original to the vehicle and i wanted to save them. Now they didnt tighten something properly and it started making a noise, took it back the tightened something and it was back to normal....i think the noise is starting to come back from the fan belts etc could the belts be slipping? and thats what the noise is? i woudlnt think so but at this point nothing would surprise me. I should have enough money to find another mechanic come wednesday so i will make sure they have this listening device your talking f
thanks for your advise