I have a set of scope mounts for a Win 70A.
What is the difference between a 70 and a 70A ?

I can't remember if there was a model 70A or not. I kind of think it was made between 68 and 72 if it was, and it was no different from any other model 70 such as the 670 and 770 which were a little different.

As far as scope bases go the difference between 70 and 70A are the 70 bases fit the pre war 70(below sn 66,500 or so) and model 54 and the 70A fits standard model 70's above sn 66,500 or close to that number. It is 66,000 something for sure.