MK64 Pintle Adapter Assembly NSN: 1010-01-151-6229. Universal Pintle adaptor (UPA) .50 cal to 30 cal/M60/M240 mount adaptor not sure on the name of the spigot insert model but these adaptors allow the old 50 cal heavy mount to be adapted for the lighter 30 cal pintle to be used along with the M60 and others they fit most Heavy vehicle mounts and we only have a limited number of these.
