in my 94 Z28(auto) when i accelerate fast theres a loud thud and the shifter shakes, ive been told it was the torque arm bushing, but ive replaced that and it still does it, everything on the torque arm is in perfect condition; all bolts securely in place. The transmission is fine, nothing wrong with that doesnt slip, miss gears, grind and the engine and tranny mounts are in good shape...none of that. What i think the noise may be is a bad differential, that the spider gears are loose then catching on. when i ease on the gas and get the gears tight together and give it a decent amount of gas, it doesnt do it, only from stop to a decent amount of gas. any imput would be awesome

 

Seriously sounds like transmission mount... If you floor it does it slap forward and then slap back when you let off? I know when my transmission mounts go out it feels like the transmission is just swinging around down there and you can feel the thud in your foot everytime I floor it or let off.

 

Even a transmission mount that looks good can be bad-

They are cheap, that is where I would start- your symptoms sound a lot like trans mount.

 

Trans mount!.....Replace it!

 

+1 on the trans mount

 

Tranny mount, been there!

 

Moving..... hopefully he finds this if he comes back.