Are you sure it is Huntmans and not Huntsman?
I was curious and spent some time searching. All I came up with was this:
http://books.google.de/books?id=uSADAAAAMBAJ&lpg=PA136&ots=F4koyFLZs0&dq=huntsman%20camper%20factory&pg=PA135#v=onepage&q=huntsman%20camper%20factory&f=falseAccording to the linked article, there was a Huntsman Co. in Pomona, CA which built campers in the early 60s.
IMO, production data for most manufacturers are pretty much nonexistent unless you can find the person who has the old records - if they exist at all. I'd be glad to be proven wrong, though...
