I think I figured out why I have no attachments that fit this machine. From what I've seen, this would have been teh "open toe" type of feet.
Greist had a "generic" set that is this way, but has a shirr plate and underbraider for a round needle plate machine. After looking around (and at some pictures listed as "Davis attachments" I see that there is another set like this that comes with the under braider and shirr plate for a rectangular needle plate. I've been skipping over all the open toed sets - assuming I already had that one LOL!!
And there are quite a few sets like this - so getting one is not going to prove difficult.