On the way back machine https://web.archive.org/web/20060414...es/carbine.htm not much information was provided about the 176 Universal and 256 Plainfield receivers. All of these receivers, to include the commercial non-military Plainfield and Universal, were transferred to the CMP by the the US Army.
At $50 each, I ordered two Plainfields and a $225 'S''G' receiver that was in the IP serial range.