1972 Chevelle 396
(this happens a good 1/5 times) whenever i turnoff my car and come back in a few minutes, i try to start car. as soon as i turn the key to start it, all the dash lights and power to the vehicle turn off as if the battery dies. i found that if i disconnect the battery and wait 5 minutes, then the car will start back up (as if it recharged???) could this be my alternator? if so what a good alternator for a 396 chevelle? something that will be able to run ac and a nice sound system in the future.