OK, Trying to do at least most of my own maintanance, however this may be beyond the scope of my ability. have a 1970 vert..auto, seams to drive ok...but if you realy lean on it leaving a stop light, it makes a loud chatter, or grinding like noise.......if you back off the throttle..it goes away and seams more or less OK. I added a little fluid a few  weeks back and it might be a little over full, if this would have any effect, but, I ussually dont realy push the car ....its old and I treat it like the classic I feal it is. Any Idea's?? Thanks E.M.

Eric, first, check the trans mount. If it is weak, collapsed, or broken, it can allow the trans to shift around under there, and the yoke may be hitting on something.
If that looks good, then sadly, your trans may be on it's last breath. If it is the clutches/band chattering, nothing you can pour in it will save it.

Will it make this noise if you put the shifter in manual Low and git on it?

Being a little over-full will not cause a problem, no matter what urban legends you may have heard. If it's way over-full, then the gear train will spin around in the fluid, and aerate it, causing the fluid to foam, which can cause pump cavitation, and accelerated wear on the pump. That's about it.

Another thought....it could also be a cracked flywheel causing the noise...Adams' Apple2007-10-17 05:16:49

Hi Joel, The car has 145K on it, the engine seams fine...had a top end rebuild about at 100K, tranny looks like it was never touched, and I am sure at some point in the life of this Vette, it was subjected to some hard use. I will try out manual first gear this weekend....will that give clue to the problem? and if it is the clutches/bands.....is that  what a standard tranny rebuild is about??  any idea of cost?? Thanks for all your help. P.S. When i put in the new dist shaft...I put in a new cross gear setup, did not put in a new button, but, the old one was still in there so I thought it would be ok.......but having second thoughts....is there a trick to getting them out to replace them? Seams like it is set in there pretty good

The nylon button in the dist is really just stuck in there...a little push from the outside should pop it out...

Trans O/H includes clutches/gaskets/seals. Average cost for a shop, if you take the trans in by itself, should be in the $400-$500 range, max, depending on your area, and any additional "hard part" damage it may have...