A little background along with the problem..... One of the guys I work with has a 2005 GMC Sierra 4X4 with a 4L60 auto Transmission (out of warranty). He is getting a metal sounding clunk when it shifts from 2nd to third. He has replaced the fluids and filter and claims that the old fluid was clean. I tried to solve it for him trying to get him to sell it and to get himself a FSB but he is still resisting. Any ideas or direction?