This is what I bought.

They were washing it when I got there. Hard to see, but its a 2018 S550. They are pulling off their decals and touching up the paint now, all of which was unexpected. Machine has 850 hours. Tires were better in person than they appear so I've decided to leave them for now.
Thanks to you guys, I went exploring under the cab:

One of the mechanics vacuumed then hosed this out pretty well. I didn't take an after picture. But there's plenty more cleaning to be done. We vac'ed out the radiators. Tested the AC.
One unexpected feature was the GPS transceiver? LoJack? Blue Force Tracker is what I know this as. Anyone know if there is a way I can find that signal, like on a home computer or a phone?
I'll take more pics and ask more questions when this gets delivered next week. Next thing on my list is a set of forks. The rental place didn't have any to sell. There are many available locally. I think 48" is best, tho 42" are cheaper and more plentiful. I think that's a sign!
Again, appreciate your help. Just in case this helps anyone, I paid $19,500 for this, which I felt was cheap for here. Only auction prices were cheaper. Prices have come down in my area, but there is still an enormous range. This same machine can be listed for $29k or more. This rental outfit was selling probably 10 of these within 100miles of me and this may have been the last one. (there must be more). They were gone in less than a week. They were listed at $22.9 and I was told, all sold for basically what I paid.