Ah the picture sure helps it is like a laxative for the mind when trying to answer one of these it sort of clears things up and makes you feel lighter. OK your knife was made after 1974 sometime in the mid seventys. I believe the S means it is stainless. This handle material was used during this period and was brought into production with Schrades accquisition of Imperial I have attached a pic of a similiar knife with I believe similiar handle material in the same pattern, it is an Imperial Kit Carson edition marked Imperial Providence RI. The blade pattern under the Schrade tang is usually called a 148 and was made in several handle materials including leather wrap. This material was used in the late 60tys and 70tys under Schrade Walden pre 1972 and just Schrade post 1972. I have included a pic of the 148 Schrade Walden in the early Schrade plastic. ( on the left ) also the Kit Carson (on the right ).
The plastic handle on you knife was another attempt at finding a material to simulate real stag. This was less expensive than staglon but not as nice ( weight, feel, ect) and was not used for long. Strangely enough a couple of years ago Schrade started using a delrin stag material which is quite visually similiar to this style of handle. ( I have not included a pic since this is complicated enough. ) The Kit Carson has no model # so I guess the 172 was Schrade designation for it. Like a lot of Schrades this limited attempt into the retail market while being fairly rare is not worth a lot of money but, would be invaluable to someone attempt in to find unusual issues. LT