blowngt2419

I drive a 2000 automatic gt and when the tranny shifts its very clunky and it when ill be going a steady 40mph and take my foot of the gas it shifts down then back up again real fast. Also the shifting when im at a dead stop lets say to back into a parking spot and i put it in reverse it pretty much shoots me back when i put it in. Im was just asking the experts if it was the valve body cuz thats my only guess. O and i pretty much know its the tranny because the overdrive light keeps flashing.