Patrick I hope you dont mind me posting your photos.
The control stand on the right side is the throttle, the stand on the left is the airbrake, the wheel in front of the brake stand is likely to set the handbrake. I suspect the lever in the front is a sanding lever for traction.
In this pic there are two levers next to the transmission casing, I suspect the larger one could be a manual transfer case shifter that would allow change in a high and low gearing range between the motor and the transmission, very common on direct mechanical driven critters (IOWs no electric traction motors) to give them a better heavy traction in lowing gear and a higher gear for normal running. Not sure about the second lever but its possible its a high-low gear shifter inside the tranny itself giving yet another gearing option. Seen a similar set-up in semi-trucks, but where trucks can have quite a few gears, I suspect this critter only had a 2 speed H-L transfer case, and a 2 speed H-L transmission. The red tank is the fuel tank. Could be wrong but thats what I’m seeing.