i know of one guy who broke his 6,5 and found a 6,2 at the junkyard....
he moved everything from the 6,5 over to the 6,2 and got decent mileage and loads of pulling power as well as it was decently fast too.... it was ofcourse no Duramax... but it is still running and does all that it has to do
And he recently installed a Intercooler and it does magic...