3500 2wd wheel bearings

I have a 2002 Ram Van 3500 (2wheel drive) It's the same chassis/etc as a Ram 3500. I am trying to replace the front wheel bearings, but keep coming up short. About 2" too short. As in, when I go to put the disk rotor back on, it sticks out too far to even get the retaining nut threaded on, let alone down far enough to put the retainer ring and cotter pin back in. I've double-checked with the parts dealer and the bearings I have are the correct ones (National LM102949) according to the sources they have. Any help? I'm desperate! Dan Baker