I am the 2nd owner of an 04 F350 DRW 4x4 Crew v10. Truck has 42,000 miles and this past weekend I changed the rear and front diff oil to Amsoil Severe Gear 75W-90. No friction modifier was added and no chatter has been present. Also changed the transfer case fluid to Amsoil ATF and also thoroughly flushed the power steering system with Amsoil ATF and the whining pump is now silent. Everything went well and next on the agenda is to replace the brake fluid when I get time. Then I can relax!