I came across these OEM center cap inserts on Ebay, and thought someone might need them. I believe that they are Ford parts. They are inexpensive and if your caps are good other than the centers being ugly this is a cheap fix. I'm not selling these, so they aren't mine.


eBay Motors: 4 New Ford Truck F 150 Hub Cap Centers 4WD Wheel Drive (item 260298700394 end time Nov-09-08 13:33:28 PST)

 

I'm not 100% sure they are original Ford or not, thats a good price though.
I bought a set of 4 just like them in RED for around $30.00 from Dennis Carpenter reproductions.