voltage regulator repair
Take the cover off of the old regulator then buy a new solid state one. it is much smaller, then find a way to fasten the old cover over the new regulator.
Or perhaps get a GM style solid state regulator and solder it to the connectors inside the old regulator shell. I am not sure of the actual compatibility here.
I guess what I am saying is you are better off with the newer solid state regulator.