When I am driving, I get to about 10 mph and can hear a sound like popcorn popping in a metal skillit. It only happens when I am rolling and happens when I am both pushing the gas pedal an not. It sounds like snapping-metal creaking- poping all out badness. Seems to be coming from tranny-transfer case. I am wondering if my transfer case is out of tranny fluid. I have a leak coming from the back of the transmission. The 'rear seal'? I'm gonna try to top off the xcase tonight. Any other ideas? It sounds like I am killing the poor thing. I have an 82 K5, stock drivetrain. 350 4bbl and a NP208. Pretty sure it's a 208. Thanks a bunch! ps, not sure what tranny, basic K5 though. What will a tranny rebuild set me back?