if you get a duramax dont get a lb7 01-04, the injectors are "internal" and junk. The lly's 04.5-05 are great but come from the factory with a restrictive turbo mouthpiece that restricts flow and causes minor overheating. lbz and lmm are good also 06+. I picked up a 05 lly single cab long box 4x4 with the zf-6 manual trans from the orginal owner with 70,000 on it. The dirtymax with the 6 speed stick is fun as shit to drive. Hard as fuck to find but worth it. Threw on a afe mouthpiece and shes good. Just stay away from the 6.0 ford unless it has head studs and the egr blocked off. buddy has 240,000 on a 6.0 and it runs great. On the other hand my old boss just sold his 94 12 valve dodge with 413,000 miles. ran great but the body was SHOT.