Inliners International Forums General Discussion Drive Train rear gears

Hi,
I just bought a 79 Chevy C-10. It has a 250 inline 6 and a 12 bolt rear. How do I tell if I have a posi? Also how can I figure out what gears I have. I also have a 12 bolt rear that came in my 76 C-10. The 76 is currently undergoing a full frame off resto. How can I tell if the rear on that is a posi, and the gear ratio? It is currently sitting on jackstands in the garage. ( the rear axle)

Thanks for your help!!!

First thing you do is look in the glove box door and see if there is an build sheet glued in there. If not mark the drive shaft and the rear wheel and turn the drive shaft til the rear wheel goes around once. Counting how many turns and parts of a turn it takes. If it takes 3-1/2 turns of the drive shaft then you have a 3.55 or 4 plus a bit would be a 4.11. Make sure both rear wheels are turning together or your figures will be wrong.

Thanks for the help. I will check on Tuesday.

On a non posi rear one tire may spin in the other direction as long as both are off the ground and in park. A posi will not turn if both are off the ground and in park. If i remember my non posi right hope this helps }[oooooo]

The rear end for my 76 chevy truck is a 12 bolt. However I have taken off the wheels, drums, and I took out all the wheel studs. Im getting ready to clean and paint or powder coat it. Before I do all of that, is there a way to tell what gears are in it and tell if it is a posi? If not I will find out after I dis-assemble the rear end. I have never done this before. I know I need a dial indicator to check backlash/endplay. What else do I need to know? Any suggestions on books I should read? Im hoping to have the truck done by mid September. Any help is greatly appreciated.