Hmm.. A diesel pusher for under $20k.
Watch out on this one. I like the Safari magic bed thing, but I know to watch out for those early GM diesels and associated chassis issues. I found one post about them:
The transmission is likely an Allison FOUR speed automatic with a GM diesel that was used in pickups. End result, was overheating, vaporizing the sump oil and boiling out the radiator. On the road the vehicle would fishtail and weave due to inadequate suspension.
Do not take that as gold. There is a Safari owners forum and they do have a following - ask the guys that know
what is required and the details on that particular coach. I don't necessarily it's a good deal.