[JesseK]

I'll make a plug for WCD ("West Coast Drive") here. The concept of the frame setup, wheel blocks, live axles, cantilevered wheels and tensionless chains all cobmine to make it a great, versatile drive setup. Our team will do this next year since we proof-of-concepted the first sliding block in March. It took 2 hours to make the block on a manual mill, but we feel confident we can get that time down.

WCD itself isn't the answer to everything related to drive train -- yet it is the one "baseline" drive train that allows for the most design adjustments (# of wheels, wheel diameters, wheel types, tread types, which gearbox, etc) in the least amount of time. Adding extra features (like a drop-down caster/omni) is very easy as well.