I was going to note that there were two types of sears for the Fulton box locks but since then you have stated it is the very early type used on Fulton's and Sears Roebuck Gladiators made by Hunter Arms. I refer to that type as a "swinging" sear and is noted by the top screw on the receiver. I can see why they did away with it, not the best way for a sear to be.
Glad Travis has one for you.