Welcome stanzuray, here are pics of my '86 M1031 contact truck which is what yours is. The throttle actuator on the engine is for the 12KW generator in the back. The gen runs from a PTO on the transfercase and uses the actuator to maintain 1800 RPM under all electrical loads. There is also a 3 phase air compressor back there. I am assuming yours is still in place as some trucks went to auction missing equipment. My truck has a confirmed 6888 miles on it and other than faded paint is the cleanest Mil truck I have ever picked up. It had a bunch of tools in it too. I wouldn't be surprised if your truck mileage is actual as many of these trucks did sit for a long time. As stated before, look under the truck and at all the high wear points and you will know if the mileage is correct pretty quick.