I'd like to know if you can run a "new" 12 volt retro sun tachometer through a 6Vpos. to 12Vneg. power inverter, that's the only thing I would do with it. I have a 6V postive ground 55 ford. I see some 6 volt tachs with transmitter's on sale in e-bay but, the transmitter needs batteries, try and find an old 3 volt battery for those things. There is a place you can have a Sun transmitter rebuilt to be fully transitor but how much would that cost?......anyway looking for some feed back here...(No I don't want to change car over to 12V just for the Tach).........Thanks for reading this post.....Dave
Find one of the tachs from the mid to late 60's some of them were transistorised and some were for 6 volts, I had one as a kid.