The 06 van engine is basically an LBZ, but the ECM is pinned differently due to the 4L85E trans. The trans will be your limiting factor though as teh 4L85E just can't handle alot of torque. There will be some pretty big differrences between teh van and the truck engine though as far as teh plumbing goes as teh intake is completely different between the two. Member pussow at thedieselplace.com has done the van engine into an 86 body style truck and would no alot more about the mounting differences.
1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, 3.42 gears, 261 T-case
Trans has a mild build with ALOT of help from MIKE L. which included ALTO's for C1-C4 and a PI ML converter
DIAMONDEYE 4" exhaust with a CORSA muffler, AFE stage 1 dry filter, EFILIVE, KENNEDY single pump and pump rub kit.