alternator help?

[jdhurd]

I think my alternator is dying. NO starting problems, but with engine, blower, and stereo (no amplifiers, 4 speakers) running I get the low voltage light. The gauge reads real low also. My 91 sunsetter has a stock 55 amp alt. Should a new 55 amp alt fix problem or should I get one with a higher output? If I decide to add one amp to my stereo will I be screwed with a new 55 amp alt?

[electricjohn]

Voltage should be a bit over 12 on key up and a bit under 14 when idleing.