I am fairly certain that they are interchangeable. The trick would be knowing if the main body casting no. is alike, but the main body was not serviced separately by FORD.
What I have found is that most have separate service nos., but that would be mainly due to timing curves and drive gears being different on early MEL because of all the cam change design.
What someone needs to do, is look for Casting I.D. Nos. on a distributor housing. One should be stamped and is the Assembly No. (12127) and there also should be another for the housing itself (12143).
The O-Ring will fit in the MEL sleeve and the valley cover will sit on top of it, so they should be the same in that instance.
I have one here come to think of it. Guess I could make the search myself.
