between 1996 and 2000, all GM trucks uses the L32 Small Block Chevy. after that, the 1/2 ton and 3/4 ton trucks used the LS motor, and the 8.1 liter big block. some of the vans continued with the SBC until 2004
boats continued to use the small block until 2014 when GM industrial motors switched everything over to the LS/LT motors except Mercruiser which built their own blocks and heads for their 4.5 and 6.2 liter motors
your 2006 motor is the same block, heads, crank, rods and pistons as the 1996-2000 GM trucks