Those sockets look like the same ones used on the Canadian bren carrier convoy lamp as discussed here:
http://www.mapleleafup.net/forums/sh...ad.php?t=16162
Here is a link to the photos I posted of my convoy lamp. They used an adapter nut to go from the socket up to the typical cmp tailamp housing.
http://www.mapleleafup.net/forums/sh...536#post143536