Mustang generator cars by VIN for 1964:
Dearborn - C5Fxxy100000 thru C5Fxxy249999.
San Jose - C5Rxxy100000 thru C5Rxxy125000.
Mustang alternator cars by VIN for 1965:
Dearborn - C5Fxxy250000 to end of 65 production.
San Jose - C5Rxxy125000 to end of 65 production.
Notes:
"1/2" left off for brevity. (You should know that by now.)
Not every six digit portion of the VIN was a Mustang.
"xx" is body style number (07, 08 for 64: 07, 08, 09 for 65).
"y" is engine code, D, F, U, K for 64, A, C, K, T for 65.
"K" code engines were the only common code for 64 and 66.
As stated by Charles, no 64 production Metuchen Mustangs were built.
Jim