Converter problem?

THanks for the replys

Called a buddy at a tranny shop and he suggested I bypass the rad cooler with a piece of rubber hose and try it in reverse again. So I take some rubber hose and try it in reverse and WHAM no more problem. I do not know the status of the rad prior to me owning the car . THe transmission never gave me any trouble before and the fluid is like new at the stick.
I am going to hang a Tran cooler out front bypassing the rad and good to go for the rest of summer. Seems to be a first check beside the fluid at the stick at this guys shop when it comes to older Chryslers.