I have a 71' camaro with a 350/th350. The tranny has no problem till I shut the car off. Then within a half an hour it gushes out fluid. When the car was built, I put new gaskets and filter in it. I tried flopping around the cooling lines but that didn't work. I am lost right now and would appreciate any advice.

does your trans fluid tube say that you are low on fluid? If it does, and you keep filling it, the tube may be the incorrect length if it isn't stock. In that case, you are overfilling the trans and it will belch fluid out of the overflow once the car is stopped. I had this problem, just stopped refilling it and now the problem is gone. If you spot the fluid coming out from somewhere else, then you could have a problem.