It is not a common pattern, and was not listed in the catalogs. The 893 you describe probably has delrin scales, and was likely manufactured post 1973. The last catalog date of the 3 blade version, the 895, was 1979. Some two bladed stainless versions, with a Schrade 825 stamp, turn up from time to time.
Stamping is possibly Schrade/893 USA? Does your example have the words you described etched or engraved on the sheepsfoot?