Hi David,
There should indeed be two holes, though the lower one is usually the one through which the mains cable passes.
Here's a pic of one I restored a few years ago that I found on my PC. Obviously, the Nylon P-clip is non-original (though I think it looks nicer and works better than a knot), as is the gold coloured cable (mine had had its cable snipped off prior to sale).
I have seen the upper, recessed hole used to mount an external LS or tape out socket, but done by a dealer rather than at the factory.
No legs were ever fitted as far as I know. Certainly my four just have tiny rubber feet.
Look out for the OP tx being open-circuit on one half of the primary
Nick.