Something clunks when it shifts into 2nd gear. This only happens at part throttle during normal driving. I thought it could be the rear end at first but I twisted the driveshaft and there was no play in the rear end, but there was play in the transmission but maybe that's cause it was in park on a lift. It doesn't clunk when the trans is cold, only once it warms up. It still shifts solid but it seems like something is funny cause it only does it on the shift into 2nd. I also tried raising and lowering the shift pressure offset in LT1 Edit. It didn't stop the clunking. I have a trans-go shift kit installed in my trans. It's been in for 2 years now and I have not had any problems. It's the original trans with 80K on it. Any ideas??

Thanks