I'm replacing all the flybridge gauges of my new to me 1987 36' Mainship (twin crusader 270's) because the years of exposure have taken their toll. I bought "Coral" style Faria gauges which are a decent match for the obsolete medallions. All the gauges have been easy to install with identical connections except for the voltmeters. The new Faria has only 2 posts - one designated (+) and one G. OK easy enough - but my original medallion voltmeters have 3 posts - a G with several black grounds , a P with the purple ignition wires and an S which has 3 thicker gauge red/orange wires. Yikes! Would all these go on the (+) of the Faria or do I need a different type gauge? Any help is greatly appreciated.

