We have an 08 40' MDTS and I have looked nationwide for filters. I have used Tennessee Filters in Nashville, TN for the past three years and they blow the competion away with low prices and great service. I find I can order the filters from them, have them shipped to Idaho and still come out well below local sources. Thier info is: www.tnfilter.com
92 Woodard Ave. Nashville, TN 37210 615-244-1626. They can cross reference any filter and they provide OEM Onan filters also for your generator and filters for your Aqua Hot and Hydralic systems as well. Give them a try, I am very satisfied.