I just inherited a 76 K10 and the 12 bolt rear ended seems sloppy. When i get on the gas after letting off I hear a clunk. When I grab the driveshaft I can turn it about 40 degrees in either direction and the U joints all seem to be tight. When I talked to the guy to gave it to me he said that him and the guy who restored it went through the rear and and everything seemed good so they didn't do anything except clean it up. What do you guys think, should I bring it to a specialist?