We have a 2006 K2 by Komfort 21ft toy hauler. The maker said I should have the 3500lb Dexter axels but I have 6 bolt 15 inch rims with 225 75 15 D rated tires that would strongly suggest to me that I have 5k axels instead. I have been under it and looked from one end of the axel tubes to the other and can find no markings. How do I find what brand axels do I have?