"I might be able to sell the rear wheels and scrap the thing out and still put the deal together."
I think you are on the right track here.
The tires should most likely be 30" or 38".
They would sell readily as a lot of brands and models used them - especially the 38s
I have never owned one of those 6000s or Commanders but from reading these boards for 10 years I can tell you I wouldn't give you much of a trade for one. Like if it has new tires in the rear maybe a couple grand is all.
If a guy knew those tranctors and the trannies in them he could keep himself in cheap horsepower for a long time.
But for a guy who is looking to make a buck off of one I'd say they are mostly a losing proposition.