I think he shot himself in the foot. The only reason to take the pan off is to try and figure out what's wrong, or hide evidence.
A serious seller wanting top dollar for a previously rebuilt unit would leave the fluid in it and the pan on, until the buyer shows up. Pan stays on until money is out, and sale remains contingent on it not being full of crud when opened.
That's the only way to prove its worth more than a core IMO.
Motorhome transmissions don't seem to be plentiful, but they're also not in huge demand I don't think. The real value in the standalone trans is that they don't come with a "free" motorhome attached! Hah.
