I have an '89 C951 and haul it on a '92 F-250 w/pretty beefed up suspension (I regularly haul close to 4k lb in the bed). I'd be really leery about hauling it on anything less than a ¾ ton w/an 8' bed although as you said, the PO had a 6½' bed and it seemed work but certainly couldn't pull a trailer behind it.
If you do decide to sell the camper, please let me know - Has nothing to do w/what I said above
. I'd rather see you get a heavier duty truck & keep it. I really like mine as it's the perfect length to still be able to tow a trailer yet have a full bath but yours appears to be in much better condition than mine & I'd poss. be interested in selling mine & trading up. Shoot me a PM if so.
Edit - Just noticed how old this thread is.