I believe you are referring to "set Screw , belt feed cover pivot" The federal stock number is 5305-558-3689, which means nothing to anybody. It is shown as item 1A of figure 5-26 in TM 9-1005-212-35 September 1965. I don't know what SARCO calls it if they have them at all. Sarco seems to assign their own name to the parts from time to time. It might possibly be what they refer to as "belt feed lever bushing nut" (catalog number A4033) but it would be best to call them to be sure.