R/RYG. An end-of-siding three-head interlocking signal, catenary-mounted with about a 6-inch spacing between heads, located a few feet higher than kuid_481384:11110045. This would typically display medium or limited speed indications, and restricting. I'm not aware of this signal (or any two-headed signals) being used for interlockings, since the Reading almost always used three-headed signals for that, but it's likely Conrail employed some of these.
Updated by CRG.