Actually the last time I talked to Chance (DuramaxSuburbans.com builder) he had called to forward some work to us and offered the URL (for a price), I think he is out of it now.
The GMT900 platform is very tricky, not for the do-it-yourselfer and you must have a GM franchise TIFFs Acct to do...
Yes and No,
The American Axle 11.5" is in our opinion far superior to the sister version by Dana as the 80 series, due to the additional pinion support, but as for the Qudrasteer diff's they were built by Dana under the 60 series with a 9.25 ring gear for 2500's. I don't know about the 1500HD...
Actually the 9.25 Dana 60 Qudrasteer is the only one that was decent. It holds up well to our 450HP/700FTlb Duramax SUV's but I wouldn't recommend it for anything more then that. It is a neat system and we have another one here right now that is getting built in a few weeks...