SBC problem - Cannot start or hold a charge. Possible electrical drain?

Starter checks out. Alternator checks out. New battery cables. All connections/grounds cleaned.

Jump it from another car (running) with flimsy cables and it will hardly turn over. Jumped it with heavy duty cables and it starts right up.

Ran it for a half hour. Voltmeter reads 14.6 +/- when running.

Stop truck and it won't restart. Not enough power for even the headlights.

Had battery checked. Dead and will not hold a charge. Battery is 2 years old, admittedly truck hardly used.

Possibility of a drain? Only place I can think are the courtesy lights in the door and overhead.

Going to put in a new battery but am concerned that there still might be a drain. Any ideas would be welcomed.


1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice