97 chev 4.3 alternator

recently the battery on my 97 chevy 4.3 started losing charge.drops from 14 to nothing in about fifteen minutes of driving. i replaced the alternator with no change in results. what else could cause this? voltage reg? also replaced battery same effect. i know there are different amps of alts, but how do i know what the original was. with the new alt im only getting 11 volts off the alt when should be close to 14

Do you have 12 volts on the small brown wire with the key on engine off?
If not check the gages fuse.
It is not uncommon to get a bad alt sometimes.

yeah i have 12 volts to brown wire