You have 3a on yours, correct?
Looks much like 3a/3b, yes.
The "ink-stamp type, C7AF-11001-B" starter I have restored was purchased online as "used", so no other history except that it looked "old" when it arrived, though it worked OK on a bench test however it was in need of overhaul once I inspected the brushes (meaning it very well could have been in "much used, original condition").
No 100% way of knowing the "cover" is what would be typical on a November, '66 built SJ example.
This detail might be rather difficult to determine for starters that are already installed, excepting a form of Braille I suppose. I am a little surprised there are not more comments over this detail so far, perhaps other members are doing research?