I have a 1999 National Tradewinds with a 300 HP Cat on a Freightliner chassis and like it. On mine there are two fuel filters. One on top of the engine (you have to raise the bed). The other is in the bay on the left side. Some filters have a petcock where you can drain the water but the one I presently have installed does not. Draining water every time you fuel up is not always necessary. I try to buy at stations that sell a lot of diesel and change that filter about every 10,000 miles. I have about 95,000 miles on my MH and I have had minimal issues. The Generac generator and the dash air have been an issue at times but once fixed work fine. If you need details on this coach PM me and I will gladly answer any questions you may have.
Arnold