Mopar alternator has too much output

Howdy Gang,
There is a big 12v Mopar alternator with solid state reg from the late'70's mounted on a Clark Skidder (logging equipment)with a V-6 Cummins diesel.
The Ampmeter only goes to 40 amps and I'm pretty sure the alternator puts out a lot more as the gauge is pegged+40 just after starting
then the circuit breaker trips- amps to zero
then the electric fuel shut off kills the engine.
I'm thinking on using a car heater fan Resistor to cut down the voltage from the voltage regulator to the positive brush.

Will that work?
better idea?
thanks
hank

Silly question, but have you changed the regulator?
Those things will ground to it's outer case and make the alt go full charge.
Not an uncommon thing to happen with those regs.

thanks for the replies guys
the ampmeter is factory installed without a shunt
twin 4D batteries(new)
I'll try another reg and see what happens
hank

Tried another used regulator and got the same results
at idle it would put out 20amps and if I rev the motor it pegged the ampmeter
then it would trip the breaker and then the motor would die
so I installed the resistor
and all is good
just a slight 5amp charge at idle and when I rev it 35amps
the breaker didn't trip all day.
The skidder is quite old and came with a low output generator12v 30amp
I figure the alternator just had too much power but with the resistor it weakened the field and lowered the alternators output

I get fire wood for getting it to charge
thanks guys
hank