2001 Tahoe, pulsing lights, alternator issue???

[Pepsi Max]

Hi

Having issues with the lights on my Tahoe 2001, Z71 4WD,

When the engine is running the lights on the dash and exterior lights pulse (flicker)

I think it is the voltage regulator in the alternator, am I right?

If so, what amperage alternator is fitted to my Tahoe, 105, 130 or 145 amps.

Thanks for looking.