Wow! And welcome aboard! To find out how all systems run, since I doubt you will find manuals for something that vintage, you might want to check out some of the RVing books available - here's a link to some at Camping World - http://www.campingworld.com/search/index.cfm?N=1152&affiliateid=4232&perPage=96
Look for ones like RVing Basics and The RV Book. Won't have specifics necesarily, but it might give you a better understanding of how your systems are supposed to work... As far as the van itself, just use a regular service station/Chevy dealership for work - nothing special about that... Regarding your propane tank, if it is permanently mounted versus a removable 20# bottle like on a gas grill, technically it does not need to be replaced. However, it might be worth a trip to a propane gas supplier - even if they don't work on propane systems they could probably give you a lead on who might... Most of this work could be done at an RV dealer/service center, but honestly that would be very costly, particularly for a $900 van! Hope this helps. ST
