Hallo folks,
my Frog still runs on positive earth. I don't have any problems with it. There are always enough amperes and volts to drive even in the night!
You're right saying today its easier and cheaper with neg earth. I can't see any reason for me to change to neg earth at all.
My Frog had had some changes before I bought it, the whole gauges are form Sprite 2. There is a pos earth tachometer included not the mechanical.
To change a tacho from pos to neg or the other way is no problem if you can solder. There are only a few wires to change!
I got a plan for an MG B in my computer, but it may be in German.
But if you visit my homepage
http://www.ragnars-frosch.de/html/reparaturtipps.html there you can find a report form
Marc Olson (you have to click on his name) who lives in the USA. He describes all you have to know about the tachs. To get to the English part you have to scroll a little. Also you can find there some firms who can help you if you click on
Firmen.
Running on with positive vibrations on heart an Frog