I took a closer look this am. The phones are meant to mount on the screws of a standard single gang electric box or LV plaster ring. At least that's how they line up. I searched the internet for "telephone adjustable wall mount plate" and found nothing. Also searched "wall Jack" and "630A jack" and found nothing that would work. So I guess, at least for now, I'll continue to mount them off to the side or above or below the 630a on screws into a stud. I suppose if it were over a plaster ring or single gang box you could just put a 42a mod jack in the box or wall and mount it that way too. Probably one of those things that should be looked at instead or doing a Rube Goldberg type install. Once again not a show stopper though.
So are you saying that there aren't two "bottom holes" for the mounting lugs?
Missed that part of your question Ed. No there are not.