Another one for identification Please

As I continue to wade my way through my recently deceased dad’s knives collection, I came across another spyderco that I cannot identify despite trying to do so. This one simply says spyderco in one side, seki-japan on the other side. The clip reads “US Patent 4347665 Foreign Pats Pend”. This is an absolutely vicious and serrated curved blade. Oh, and I am sure it goes back several decades.

Any insights would be appreciated.