Although I recall hearing there were a couple of minor differences in the first green dot C6s I don’t recall anything affecting the strength of them.

I originally built the FE in the 64 Ford for a 61 T Bird I used to own and had I kept the car and installed the engine in it I would have used the green dot C6 in a heartbeat.

I used the later C6 in the 64 strictly for the shift pattern.