1953 Chevrolet 3100, converted to 12 volts with alternator. Drove my truck today and amp gauge shows charging max all the time. Battery was almost 5 years old so I replaced it. Same charging status with new battery. New battery showing 13 plus volts with engine off. In the past at start up, amp gauge would be in the middle or minus until engine rpm rose up, then show plus charge.

So, can the alternator fail in the "charge only" position?

Alternator is 7 years old but not many miles on it. One of these:
http://www.oldchevytrucks.com/cart/index.asp?sdes=rehp136

Can I buy one at a FLAPS?
Thanks for any input. Joe