Okay looking for opinions. I have a SM465/NP208 combo on my blazer. When i let off the clutch from 1st to 2nd and apply engine torque to the trasmission i hear a clunk sound coming from the drive train. it doesn't do it on any other gear change. The transmission bushings look good and are tight still after 20 years. The U joints all the way back look fine. maybe transfer case belt slack? THanks in advance.