Bad Battery, Starter, or Alternator?

[sandorjoben]

Scenario:

Yesterday went to take my 1987 V15 w/305tbi to work, battery is drained(thought I left the parking lights on, but don't remember now if the switch was pulled out at all). Boosted the truck after work(took another family vehicle), and took it for a good long run, went out later last night ...started fine.

This morning, took the GF to work... started fine, stop at home for 1/2 hour this morning after dropping the GF off at work, go to start the truck to go to work... dead, no lights, nothing, also, I definitely did not leave the lights on. Go to boost the truck, lights work with the cables attached to the good battery/vehicle, clicking sound and slight(1/2 sec) turnover attempt then only clicking, but no start, left the cables on for 10 minutes with other car running, try again, same thing. Disconnect the cables and the battery remains completely discharged. Repeat process, same results. Get a ride to work, truck is dead. Suggestions?

Dave