Same here, back of my rear axle looks better than front. See photos. It looks like either Ford or the axle supplier put a very thin coat of paint or none at all on the rear axles of our Raptors.
I had the spare tire off and checked the rest of the truck under the bed, frame, and mid section. Everything else looks good but living in the desert I dont expect to see any rust.
I have to bring my Raptor in for the latest recalls and the TSB's. Im going to see if they will spray the rear axle black or undercoat it while its in the shop. If not, I'll do it myself. Jeez, even Toyota paints their rear axles black with enough paint to prevent rust!
Aloha, HT
View attachment 119671
View attachment 119673
View attachment 119675
View attachment 119676
View attachment 119674