you've got a number of issues against you.
one, Vanguard sold very few campers(course you don't even say what kind of camper it is, TT, 5th wheel, popup, etc..)
two, because there are so few of them around, seriously doubt someone will respond.
three, you're asking for a owner's manual from 40 years ago.
and you don't even provide a model number.
Dan- Firefighter, Retired:C, Shawn- Musician/Entrepreneur:W, Zoe- Faithful Golden Retriever(RIP:(), 2014 Ford F150 3.5 EcoboostMax Tow pkg, 2016 PrimeTime TracerAIR 255 w/4pt Equalizer and 5 Mtn. bikes and 2 Road bikes