Cage nuts will be found in a variety of places on the MGA, mostly in the body assembly, because the parts are spot welded together. Most of the original cage nuts will be a fine threaded square nut inside of a single piece sheet metal box with wings spot welded to the body. These parts are most often found where access to install a nut is difficult or impossible. Some will be found inside a body post where it would require cut and weld to replace. When the location is accessible you maybe able to bend up a tab on the side of the cage to replace the square nut inside, and bend the tab back down to complete the repair.

Most of the cage nuts in the MGA will NOT have a part number in the Service Parts List, because they were originally welded into another assembly, therefore being non-serviceable. Find a list of captive fasteners for the MGA in tech article CF-160 in the Care And Feeding tech section. You could make your own square nuts from flat stock, cut square, drill and tap. You can make your own cage from sheet metal, cut to a cross shape, one hole in the center, and folded to suit. Replacement cage nuts may have a two piece sheet metal cage crimped together to retain the floating nut inside until the assembly is installed. Cage nut assemblies are available from McMaster-Carr in the U.S., and here are some of their part numbers.

  1/4 x 28 - 90955A113
  5/16 x 24 - 90955A116
  3/8 x 24 - 90955A120