6.5l NA engines because they are A2 series trucks. But at least it makes it easier to upgrade to a 6.5l turbo later, it already has the 4L80E 4speed transmission and TCM, 242 TC and driveshafts installed. I'm looking into the other alterations needed, like opening up the transmission doghouse opening and replacing the transmission dog house with the larger turbo cover. I wouldn't think there would be any additional lines or wiring needed.
Considering the ex-USMC M1043A2 and M1045A2s have been selling for $20,000 + for runners, some missing doors and seats, and, the turret Weapons Support Assy, B Pillar tubes as well as C Pillar removed for sale, these at least have the Weapons Support Assy with B Pillar Tubes. Either buy the remaining slant back sponsons, crossbar and hatch $2500-3000; or hold out for an original GMV Charlie Pillar (I just bought one for $850), an original MSG C Pillar $1000; MSG Side Assault Cargo Rail Kits $1800; Repro GMV 1pc Charlie Pillar $1850 (mcad33 on G503); Sheetmetal Bed Side Panels $350 (mcad33); D Corner Brackets $175 (86HMMWV); Sheetmetal Bed Side Panels + D Corner Brackets $850 (Dave Liland). Or convert a pair of 1025 sponsons to GMV C Pillar if you have welding skillz. Add missing turret parts $2500-3000; High Back Seats $250-300 each;