Here is the MPC ENGINE/AT combinations for the 1964 LT -

The C4 was not used on the 1964 FYB LT.
It would not have made sense to cast a one year bell for just a one year model run and the C4 most likely would not have taken the punishment the C/M could.
C = 1960's
4 = 1964
A = FORD CAR
P = POWER TRAIN
7976 - BASIC ENGINEERING PN For A BELL-HOUSING
C = Would Indicate Exact Application
C4 Would Indicate Release Year
A Would Indicate FORD Pass Car
The FYB Was Last Used On The 1962 PASS CAR - LT/MT 1964
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