The new GM Crew Cabs come with a 5.8 Short Box or a 6.6 Standard Box. The 5.3 is a $1200 upgrade, look for one in the W/T trim to keep costs down. There are some around, pretty sure I saw a few at Tyee Chev here in CR. The W/T has a rubber floor and manual 4x4 shifter on the floor.