I tried searching but didn't find much. Is there a cut off date or any way of knowing if you have 12 or 14mm studs in the rear rotors short of measuring? I need new rear rotors for a 2000 F-150 XLT SuperCab 4x4 w/ 5.4. No tow package or Payload package.

 

Stamped on the wheel near the lug nuts is a code with the wheel size, etc.....the last digits are 14 if 14mm. The lug nuts themselves have "100" stamped on them if 12mm. and "150" stamped on them if 14mm.

 

14mm if produced on/after 12/01/1999
12mm if produced on/before 11/30/1999

Not sure, but I believe this is the "final build date."