Congrats for your new "vintage" camper!
Lance do have some historic information on their website, but only back to 1993:
https://www.lancecamper.com/owner-support/There is online information available for many/most appliances. Find out the make and model numbers which are usually somewhere on the appliance and google for them. Of course that will not help with a missing refrigerator.
Watch out for pre-existing water damage... the camper may be dry now, but it will probably begin to leak like a sieve when it is out in the rain.
Maybe you can get better answers to specific questions when you post some pictures. You can use
http://photoposting.is-great.net/ to post pictures here and follow instructions on that site.
Good luck with your new camper!