I was just trying to answer the question posed. The original Ford Racing GT caps are no longer available from Ford Racing, although I originally had them on my car. Check with Torrie to see if he might have any available.
The part numbers were:
Coolant Caps (Engine & Intercooler Caps) - M-8006-GT:
Oil Tank Filler Cap - M-6766-GT:
Ford Racing still sells the Oil Tank Filler Cap - M-6766-MP46A:
which, if you wish to keep your current plastic cap intact, can be fitted with the Mustang Cap F3AZ-6766-B plastic cap, which is considerably cheaper than the Ford GT Cap (although are interchangeable).