I have a 2000 excursion 7.3 4x4 with 200,000ish miles, I have had 2 different tuners(dp and hydra), stock and single shot full force injectors, stock, van, and van with ww2 turbos, 265's and two different sets of 285's.
I have changed unit bearings, made sure hubs are unlocked, made sure brakes...