My '79 K5's rearend (12 bolt) is making noise when I let off the throttle, even when I put it in neutral. It is a (getting louder & louder>) knock. When I dropped the driveshaft I found that there is a 1/2" of slop in the pinion when I tried to rotate it. I haven't messed with a rearend before and I'm thinking about rebuilding it myself, I built the engine so I know I can do this, but I may need a little input. How long should it take? What are the major parts to be replaced? I don't have alot of money, but I'd like to install a posi carrier, stay with the 3.73 gears, and if at all possible reuse my axelshafts. Any suggestions guys?