...Halfway along the alternator light and a few other came on briefly, then went away as I accelerated....

That is the clue. The warning lights all come on in key Position II, also called bulb test position. Then they go out when the engine has started running.

What make them go out? The lights, except the oil sender, have as their ground side a circuit that goes to the alternator brushes (the thin red wire).

At engine stop, the current flows from the battery through the lights to the alternator brush #1 around the rotor windings then to brush #1, and then to the alternator frame and then to ground.

When the engine runs, the rotor windings are actually providing the rotating magnetic field needed to generate the current, and the ground is lost so the lights go out.

What's all that mean? (1) If the thin red wire becomes disconnected the warning lights don't light and the alternator doesn't charge. (2) If the thin red wire gets grounded somewhere else, like due to chafing of the insulation, you get warning ligts with the engine running and the alternator doesn't charge.

That wire runs in a harness that wraps the bottom of the front of the engine. Miserable environment for insulation, and the metal harness holders can chafe through the harness wreaking havoc. Methinks that's your problem.

Good Luck,

Bob

:>)