Old Saw - what's up with these split sawnuts?

I picked up another saw today and it's got 3 sawnuts with no medallion (never had one). One of the split sawnuts is a kind I've seen before, but the other two don't appear to be threaded. It looks as though the one threaded sawnut was probably a replacement. How would I remove the other sawnuts? Are these an older type of sawnut, or just a cheaper version of the threaded ones? FYI, the saw has a nib and has a '5' stamped at the bottom of the saw under the handle, for 5 PPI I would guess. Way too much rust to hope to see an etch.

Thanks.

IMG_3650.JPG

IMG_3651.JPG

IMG_3652.JPG

Attached Images

• IMG_3650.JPG (64.4 KB)


• IMG_3651.JPG (83.5 KB)


• IMG_3652.JPG (133.7 KB)