The newest revision has an engineering number of 6L2Z (revision 2006) and are manufactured by *** who is a large bearing mfg. The *** part is 559431C. The originals I have seen are 1L and 3L which are revision dates of 2001 and 2003. Ford does change the part number for design changes, color changes, coated vs uncoated, supplier change, etc. So could be the 6L2Z revision is a supplier change only or design, who knows.
I have seen more failed bearings regardless of brand due to careless install especially when the half shaft retaining nut is not used correctly to preload the bearing or the vehicle weight is placed on the bearing and then the nut is tightened. Even saw one where they ground down the outside of the bearing to reduce the OD to fit into the knuckle better. Amazing