Can't help with the first two, however we were at Transicold South in Birmingham yesterday (Carrier) that had some gently used takeoffs. They were on fleet trucks that were being sold, and the buyer had no desire to have an APU. Might be something to think about. Ours has 14k+ hours and still purrs.
Sacramento 49er truck stop has rig master's and another (dynasys?) and offer financing. Ringmaster has the Perkins (Cat) engine. The other, I have no idea.
Zorry might also know some.