If you have a 240Z with just an ammeter, a display of volts would be nice to tell you how good the alternator is. You know how healthy it is by the volts. Anything under 13.8 or so and you should start having a good look at it. Also, anything above 15 volts should get you panicking! I remember a while back wanting to fit a digital voltmeter into the zed and after some searching, cheapest one I came across was from Jaycar at about $65 (in kit form). On one of my searches through epray, did a search for "LED Voltmeter" and I found some nice blue coloured LED 2 wire voltmeters for only $15. After another search, found some LCD ones for about $10 from Honkers. I bought one, installed it and took a pic at night of mine, it didn't turn out the best but it gives you a good idea. It really needs a small jiffy box and a front tinted lens to look real nice. Or even install it in a gauge and mount it. Anyway, just in case anyone was thinking of where to get one...