Locomotives are diesel engines with electric motors, many submarines are, as are huge off road equipment. The trouble with the electric motors is if you use DC you need a PWM controller, it is not as easy as just sticking an on/off switch connected to a 12v or 24v battery bank.
I am planning on building an off road machine using a small diesel to run a pump and hydraulic wheel motors, but for a RBV with the diesel engine directly running a 4x4 drive train, , the only real choice, imho, is the Cummings. Though with time, money, and brain power just about anything is possible.