1985 Chevy Camaro

Transmission problem
1985 Chevy Camaro V8 Two Wheel Drive Automatic 105987 miles

my transmission or rearend not sure, jumps alot when I give it gas in a high gear when the car has been runing longer than an hour. When I cold when I first start it up it runs fine and doesnt jump real bad until ithas been runing for awhile. Is it the transmission or rear end or could it be something else?

Ill try to explain it the best I can. When the car is warmed up at running temp when im at a complete stop at a red light when I go slow and ease on it it doesnt do it. If I try to give it a little more gas it goes crazy it feels like it is going to fall apart the front end of my car starts to jump like your going over a bunch of speed bumps close together really fast. But im not sure if its under me, (tranny) or behind me (rearend) sometimes it feels like both. Only thing that gets me is it doesnt do it when it is cold I can run it intothe ground cold and it wont do it until it is at runing temp thats why I think it could be the tranny