I am considering buying a RV ,thing is do I buy gas or diesel, if its diesel do I buy a pusher or conventional also which engine would be the better for usage, power or fuel efficency and last of all how old or does that depend on how much I want to spend. My mate has a Monaco with a 8litre cummings pusher the thing is also what about servicing he says most commercil truck centres will do cummings engines but the americans are a bit different spares wise, any body got any good ideas ,thanks in anticipation