The letters in the left column ( after the model year ) refer to the car lines to which the part is applicable.
A= Mercury ( Ford )
C= Comet ( Falcon )
D= Lincoln ( Marquis )
F= Cougar ( Mustang )
K= Mark III ( and although the T-bird was based on the same platform it was given the body line “S” )
If you’re really after an R servo kit, you can obtain one aftermarket: https://broaderperformance.com/product/r-code-servo-kit/
And even though this can be changed out externally, it doesn’t make sense without the improved lever. And of course a full inspection of the trans…