I don't know what coach you are looking at with 6V92. Prevosts prior to 1995 had the 8V92 and after 1995 were the Detroit Series 60. 1995 was a transition year with some of each installed. I would not get a coach with XV92 as they are not noted for their fuel economy. I had a 1994 Wanderlodge with an 8V92 and loved the sound. Coach had the Allison 754R which is the 5 speed with retarder. A nice combination because the 2 stroke diesels need to run at relatively high RPM and the 5 speed ensures that happens. The result was a great coach that got between 6 and 6.5 MPG. Birds of that era had, and needed, 300 gallon fuel tanks.
A 98 Prevost will have no slides and, with S60, will be highly reliable coach. It will also have the Allison 4060.
You are apparently looking older than that and I cannot comment much on the older coaches.
Good luck
