You'll find there are no solder joints in the amp gauge. It's splined contact studs were simply pressed through the shunt. The 3 pieces are in some very hard plastic.
One downfall in the rally dash is having this firecracker hot gauge in the same cluster with any gauge that has a chassis ground path. That is the fuel gauge. Even the needle of the amp gauge is hot. If/when the black matting piece would break loose and fall against the gauges, 12 volts would go through the fuel gauge. It's needle would disappear to ash in a flash. I can't know how many times this happened but I do have 2 examples here, rally fuel gauges with burnt nubs where the needles once were. Rule #1 Don't tap on the glass. LOL
Since you are installing a remote solid state instrument voltage regulator, do block the back of your fuel gauge from chassis ground regardless what else you do.
