Your knife with that tang marking was made after 1959 and no later than 1973. The actual marking on your knife should be 125OT. The OT stands for Old Timer. Even though it is confusing especially when as in your case you can only see two digits of the model. Sometimes people believe the letter O is really the number zero. It is however the letter. The handles of your knife should be saw cut delrin, ( the standard material used on this line of knives.) There should be a shield on this knife handle with OLD TIMER on it. This model number was unusual in that it was used for a single blade with liner lock ( mustang ) as well as the 2 bladed version ( no lock ) that you have. Both 5,1/4" closed. The 2 bladed version was discontinued first and I believe the single blade version has now also been dropped from production. The knife you have is carbon steel. Schrade has made some ltd editions over the years which used this pattern however I believe they were in stainless steel ( designated Schrade+ ).
What this means is that since it is out of production, the tang marking is not current, and the blade material is not presently being used for any other knives of this pattern, a replacment of any kind from Schrade would be highly unlikely. However as nice a knife as this pattern was, it is not especially rare nor is it very expensive. They are on ebay all the time 20 to 40 dollars ( sometimes less ). Unless you did the repair yourself it would cost far more to have it redone than just to wait for another one to come around. Sorry I could not be of further help. Good luck Lt