My brother (actually an electrical engineer in training) says the weaker nut is the mechanical engineer's manner of suggesting/showing a weak foundation, being the way such a large stud is attached. The studs might have been much smaller diameter or even a totally different manner of attachment conducting the current. Consider the spade terminals used at the outboard mechanical limiter found on standard panels. How GM instruments are attached is very similar to that. Just plugged in male to female conductors. So why did Chrysler have 3/16 diameter studs of several times more length than needed? One would have to pose that question to Stuart-Warner since they made these instruments for Chrysler. I'll assume only because that is what their production line was already set up for. Afterall, they made instruments for tractors and all sorts of applications that experienced much more vibration long before that got this Chrysler contract. Anyway...
I too came across a few gauges with very rusted studs and I did break a backboard to learn cutting that weak nut away with a Dremel tool was my method to conquer.
In the final year of my gauge servicing I did end up reproducing half dozen backboards from F4 fiberglass. Approx' same thickness as OEM fiberboard. Reason being, In a few cases the owners OEM boards were so water damaged, warped, and brittle that I didn't have another option. At least 1 arrived here already broken.
I can't say for certain that I still have 1 of those homemade boards here but I'm sure I still have my mechanical drawing of it. The swedge tool is a "one off" that was made for me by a local machine shop that I had once worked for. Yes I recycled/reused the OEM studs.
I image that someday when I'm gone, my junior or someone will pick it up and wonder... WTF is/was this used for? LOL
