Hi, Stromberg-Carlson also made a similar protruding nub transmitter mount as I have one on an old non-dial metal box wall phone. It does look like it would fit the large center hole on one of theses tops. I actually have 3 of these tops, all with bell/gong brackets, and all came on A.E payphones. Since 34A series payphones are shown in Stromberg catalogs, and since they used either A.E. or their own similarly styled dials, it makes sense that Gray would supply paystation bodies ready to accept Stromberg components as they mention they could supply these to fit different phone makers parts in their catalog. This would explain why more than one of these tops have shown up at southern california swapmeets as they might have been made for both early A.E. and Stromberg-Carlson parts. Russell