Measurements it's 4 & 3/4th inches tall, the rail slot is 1 inch high and 1/2 an inch side. Depth wise for hanging is 5/16ths deep.
I ended up ordering HANGING RAIL BRACKET, 1-7/16" DEEP Product Code: 32-025, in hopes it'll work but I figured I should ask here in case there is something better.
Tom from SWISCO responded:
July 1, 2020
Hello! I agree, the 32-025 is the best replacement for this old socket. I find that it works very well as a replacement.