I am putting a duramax with allison in my Yukon Xl Q-steer and need to know if I need to do anything to the rear diff. to handle the extra power? I have heard that there are some of you out there that have put a beefed up 8.1 in a Q-steer, were any mods needed for the rear end?

I dont have the answer to your question, but am very interested in who is doing your conversion. Can you pass it along?

Check out my web site, I am the one doing the conversions, www.duramaxsuburban.com

Keep in mind that the QS steering module is programmed only for the 3.73 and 4.10 gears.

IMHO, as staunch as the D60 is, I don't think that it can handle the rigors and torque of what you plan in the long haul.

On a different note, are companies now making replacement parts for the allison tranny? I know not to long ago, that was one of the drawbacks of using a allison in a build-up.

I would suggest using a custom tune like EFI etc to reduce the torque in lower gears to prevent damage to the QS rear end. The allison is easy to get parts for, and for practical purposes they are bullet proof when maintained.