Thank you Stuart and Smiley, these are exactly what I need. I still have to find a tool to set them. Derek, these are captive nuts. Other types are rivet plates which are riveted on and hold a threaded portion or sometimes have a nut that is slightly loose to allow for imprecise fitting. Here in the US we also call them Kwik nuts or rivet nuts or nutserts .Their purpose is to have a captive nut so a wrench doesn't have to be used on both sides. In the case of the Ulster, according to Chris Gould, there were/are hank nuts that attach the dash to the dash supports. Also the rear screws fixing the side panels. Also on the Ulster cockpit, rivet plates or rivet nuts are used under the inspection/access panels for the rear cardan joint and starter housing access. I don't know if the original cars used these or if they just had captive nuts welded on, but I suspect they were likely used. In the end, it saves trying to find someone to hold a wrench, or trying to stretch your arms to put a wrench on something you cannot see.
Erich in Seattle
Erich in Seattle