Is there a difference for performance or just an improved version of A? Thanks

Is there a difference for performance or just an improved version of A? Thanks

Well, I just happened to run across this in an 1973 RCA book that has a module cross-ref chart:

"MAG001B has additional circuitry to prevent vertical jitter under certain abnormal reception conditions. It is the preferred replacement. MAG001A has been discontinued, but it may be used where reception is normal until supplies are exhausted."

In any case, they are apparently at least plug-in replacements for each other.

I may have never found that!
I got a CTC-54 with vertical being to short when cold then slowly stretches out. So, I got a module coming and it's the (B). I'll post pics later.