I got my gas engine tach hooked up and working on my truck tonight. I bolted two small metal tabs 180 apart on my balancer and fabbed a bracket to mount a 3 wire prox to read the tabs. One wire to ground, one to 12v, the other to the tach. Set the tach on 4 cylinder. Works like a charm so far. I am not sure what the prox is rated for, we use both 120VAC and 12-24VDC at work and there is no tag or part number on the prox. It wasn't a 5 finger discount either, it was in the scrap pile. The tach I am using now is an 8000rpm Sunpro, but I have a 3 3/8" 4,000rpm Isspro I will be mounting as soon as I get a cup for it. 8K is kinda pointless on a diesel.
Danny
Danny