Thanks for the info cattlerepairman! I think I may just leave the FDC alone. Brutus' engine seems to run well enough. I just have to find some flatter roads to drive on. It's really nice to have the maneuverability of a bobber, but I don't have close to your payload capacity. I think the rear axle is way under rated. It doesn't have kingpins. I think it should be rated at 15,000 lbs. not 11,000 like the front axle which is has kingpins.@Dipstick , even with the FDC bypassed, the engine will happily burn the full variety of fuels (but without the FDC it will not try to compensate for varying energy density; the truck will feel fine with Diesel and feel like having more or less power with other fuels, depending on the fuel used). Bypassing the FDC is cheap insurance against oil dilution.
I am driving a "pretend bobber" right now (interaxle driveshaft between the rears removed) and while I do not notice a power increase, I do feel that it turns tighter than before.