Inliners International Forums General Discussion Truck Talk 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!!!

If both wheels are in the air, if you turn one and the other goes the opposite direction, you do not have posi. If it goes the same way, you have posi.

If one wheel is in the air, put the trans in neutral, if the wheel in the air will turn, you don't have posi, if it won't turn, you have posi, good luck.

Ed Pruss
Longmont, CO

As for the ratio, you can get a rough idea by marking the rearend flange or driveshaft and turn the rear wheel one full turn. Count the number of turns that the mark on the yoke goes by and see where it ends up. You will have to estimate the last part of the turn. For an accurate ratio, pull off the diff cover and on the edge of the crown gear there will be a part number and two numbers such as "11-39" stamped on it. Divide the larger number by the smaller number to attain your ratio. In this case, it would be a 3:55 to 1 ratio. Good Luck

Thanks for the help. I will see what I can find out this weekend.

Thanks again.