Looking at one tomorrow. I know it does not have variopilot and I know it does not have CTIS. I want to know about PTO/Hydraulic options mainly. Also, is the buildsheet someone in/on the truck?
Depends on the owner's compulsiveness, but you probably won't find the buildsheet with the truck. Unless the truck was special ordered, they tended to come in two varieties, over-the-top ones with $150K+ price tags that dealers used as demos and more of a "stripper" model closer to $110K, which is likely what you're looking at.
I can't remember how to easily check for the PTO; maybe a switch in the cab. The hydraulics, one of the most expensive options, are easy to tell . . . look for the row of connectors just above the bumper. One side only is single channel; both sides is dual channel. The transmission will be either an elaborate preselecting automatic shifter or a traditional 8-speed. Look for driver's and maybe passenger's air seats. Electrically heated windshield. A rather cool three-way tipper bed. Tire sizes varied, and check the tires for their speed rating; some tires were as low as 55 mph.
And the issue of whether it's a 26K or 33K GVWR truck will likely have an effect on registration and insurance costs and hassles. And beware of rust. From the day the Unimog was invented, its corrosion resistence has lagged behind the rest of the vehicle's engineering.