I would like to convert my original 12 bolt single to posi. What is the best carrier unit to buy for longevity and ease of swap. I want to do it myself because I just don't trust any shops anymore. I've rebuilt engines and transmissions with great success and I do have the manual that the GM garages used so I think if I take my time I will be satisfied. The tranny is a Muncie M20 so I was also wondering what gear ratio would be a good comnplement for it.(3.31?)Your input would be greatly appreciated. The motor is a 350 with agressive cam and heads. Thanks. T

The best posi is an Eaton unit. Although for street use I would be tempted to put a Torsen unit in it.

Bob.

There are no new 3.31 gears. Nobody makes them any more. The 3.42 is a good gear for all around use. The Eaton is the best posi for street/strip use. If you are planning on doing a gear swap you will need a good installation kit with good shims. Many of the shim sets are almost useless. You will also need to know how to set the pinion depth, bearing preload and backlash. The GM manual has a lot of bad information in it, like the torque for the ring gear bolts and bearing preload. You will need a dial indicator with a magnetic base, a press with a bearing seperator, a micrometer and a few other tools.