Based on your post I assume you are looking at the 35WQ-P model (the 34 and 36 were gas engines, the 35WQ is a DP as you describe.) In general, the Vectra line was considered the top of the Winnebago line for most years except when the "Ultimate" line was offered.
You can download the original sales brochure here...
Brochure
which will give you some base info on features and options.
and you can get the Vectra Owners manual here...
Owners Manualwhich might also give you a head-start.
Plumbing and electrical diagrams are also available there too.
As with any non-warranty unit you need to check things over, and it's still no certainty. Things fail. Just budget for them and understand that some of the $$ you are saving on an older model versus new may be needed for future repairs. Just part of the experience.
Do check the age of the tires; if they are more than 7 years or so then they will require replacement. Might want to ask how much/often is was driven in the last few years. Diesels like to be used and if it's sat for a while it's worse than being driven a lot. Last oil change/lube/filters? Age of batteries? Is there a generator, if so how many hours on it, last oil change?
