my cousin has an 06 chevy 2500hd 6.0 gas...on the gauges and stuff behind the steering wheel..the part where it shows what gear your in has PRNDM1 i noticed that the duramax's have the same thing and are allison trannys...so do the 6.0's have an allison or not?

Nope..the 8.1 has the allison...not the 6.0