You probably won't find a manual for it, if there ever even was such a thing in the first place. RVs usually come with separate pieces of documentation from the component manufacturers, e.g. a stove manual, a water pump manual, etc. The body manufacturer may have had a few pages of overview, but rarely anything comprehensive or even very useful. Your best bet is to identify the brand and model of the major components and then try to locate manuals for them. Some will be available online at various websites (not necessarily the component company's site) - Google will help locate them. Others you may not find, but you may find a nearly identical model that will be close enough for most purposes. and perhaps somebody here - or somebody you meet in a campground - will happen to have the same one and will copy it for you.