[67_C-30]

I'm going with a 6.5 Turbo in my '67 C-30. I already have the engine, and its an easy swap, but I would prefer a Cummins. I've had several 6.2's and 6.5's, and they are good engines if you know their quirks, but they were designed (by Detroit for GM) to be a light duty deisel. With 18:1 pistons, a gear drive timing set, a main stud girdle, and ARP main and head studs you can turn up the IP and bump up the boost, and get really decent power and still be reliable, but if you do the same mods to Cummins or Duramax, they are absolute BEASTS. The Cummins engines are used in much more rigorous applications than pickups, and they are stone reliable for the most part. The 6.2/6.5 are the cheapest, simplest diesel out there to swap over into an old Chevy.