Rebuild old flatbed, or start from scratch?

Vinsil wrote:
Too cool! I love old iron too, keep us up to date as it progresses! I'd love to see an old 12 valve Cummins in it, 5 speed and hopefully it has a two speed rear end, way cool!

Already has a 5 speed trans, and a 2 speed rear. I don't know what the current ratio is, but I'm pretty sure it's in 5.x/7.x range. While the large tires help to balance that out a bit, from what I understand, these old trucks gear out before they power out on the top end. So even going to a modern engine with much more power won't gain me much on the freeway ability end of things, unless I want to spin a big gas motor at 5K RPM all day long. I was thinking maybe I could shove something like one of the 13 speed Roadrangers in there at some point in the future. Looking at the gear ratio tables of the Eaton transmissions, I see some of the 13 speeds get into the area of around .65 OD ratios which would certainly help on the freeway cruising side of things.

The fantasy part of me really wants to drop a Detroit 2 stroke into the frame, as I think the sound of those motors working is pure ear candy...but then I've seen YouTube videos of guys driving those trucks, and I suspect I'd kick myself pretty quick after doing it.

More realistically, I think I'd be looking at something like the DT466, or maybe one of the bigger Cat motors. I know everyone and their brother loves the 7.3 and the Cummins 6BT, but I'm thinking I'd better off with a motor that was intended for a medium to heavy duty application even if I'm not moving that much weight right now. Part of the reason for going big with this truck, so to speak, was to future proof myself a bit in the event I do decide to go stupid big weight wise.

On the other hand, I really don't know much about the diesels, and part of me is really thinking of staying with a gas motor just out of familiarity with them despite knowing the fuel mileage will be in the toilet doing so.