As I said, thankyou for posting the information ID'ing this knife. It seems that every knife which does not fit the known published photographs of the type is now claimed to be a "rare prototype" or some such. I left the post about this knife with a series of question marks, and thought that suggested plainly that I just did not know what the knife was. As with you, sometimes subtilties just don't translate well. That is why I added the smile emoticon.
Sellers of Sears knives have been confusing the buying public for years, claiming to know who the SFO manufacturer was, as illustrated by the "Schrade claimed" Camillus knives up earlier in this post. Now, identifying them all as Camillus knives, in spite of who their "daddy" was, is in vogue.
Do you know what plastic Colonial was using on their LB125 (and probably other knives) if it isn't Delrin? Is it another composition of Nylon, or closer to a polyethylene?
Michael