700R4 clunking problem

[Elpresidente]

I've got a 700R4 in my '82 C10.
When shifting from Park to Drive/Reverse, there is a clunking that sounds like someone smacked my floorboards with a rubber mallet.

(This also happens when shifting from Drive to Reverse, or vice versa, and sometimes on acceleration from a stop).

It upshifts and downshifts fine, with a minor clunk occuring only between 1-2.

I just rebuilt the rear end & did the U-joints, I can safely rule those out.

Ive owned the truck for 2 years and it has done this since day 1, but the problem hasn't gotten any worse or better even though it is daily driven.

Its a small problem thats starting to drive me nuts because I can't figure it out, any help is appreciated!

[screamin86]

Check your transmission mount it may be torn or wore to the point where the bolt in the center has seperated from the rubber mount. I've had this happen to my 86 trans am and about 5 times in my 82 trans am since I was using a stock rubber mount and a hard shifting th350.

[Irish_Alley]

Rubber mounts, u joints or rear. Since you say the last two are ok. Im with scream for ice cream. I bet it’s the mount try to move it up and down side to side. Or even if its oil soaked

[Blazin]

Transmission mount for me too.