I am converting my 98.5 to rear disc and I need the dimension from face of rotor to wheel mounting surface on the rear wheel hub of an '01.5 or '02 dually. I am using the 02 rotors and calipers but it seems that I will need to space the rotor back off the wheel hub in order to clear the calipers with the inside dual rim. If I could get this measurement it would be a big help!

Thanks