tachometer connection question

I was just wondering if anyone knows what each pin (marked A, B, C) at
the rear of a G.E. type E-9A tachometer (serial no. AC42-65950)
connects to? I am assuming that the connections are similar to an
automotive tach, is that correct? Will trial/error testing hurt the
tach? I am trying to retrofit some P-51 gauges into my 1968 Mustang
(car), and could use any tech advice offered.

Thanks,
Mike

"They don't make 'em like they used to..."

unless your Mustang has a tach generator, it will not work. that system has no
power inputs, the generator creates a low voltage that is sent to the tach, the
tach is nothing more than a sychronis motor. Wiring is very simple, A to A, and
so on.
Matt Gunsch,
A&P,IA,Private Pilot
Riding member of the
Arizona Precision Motorcycle Drill Team
GWRRA,NRA,GOA