Just finished this build, Its a LBZ block. This will fit in any of the trucks, 2001 to 2008. And even the medium duty trucks.

LBZ block, bored .020 over with torque plate, maged, tanked, and line honed.
LBZ crank, keyed, wet maged and polished
R and R rods
LB7 piston, deliped, .040 off the top and coated
Socal baby camshaft
ARP main studs
Clevitte H bearings
Socal dampner
ATS flexplate
Balanced rotating assembly

Price is without a core returned
$13173.39