Intermittent Charging Problem

[Maxedoubt]

My Significant Other just gifted me an '86 Power Ram that she's had for years. I had to put a battery in it, and I noticed the OIL and BATT idiot lights didn't come on with the key (no gauges yet) but it started right up and ran fine, with BATT light ON. I pulled the "T" connector from the alternator, along with the blade connectors in the "feeder" wire from the + cable terminal, flushed everything with WD-40, connected/disconnected everything a few times, then hooked everything back up. PROBLEM SOLVED! Idjit lights came on with key, engine started/ran fine with NO warning lights. THEN: Next day (today) I loaded the truck for a dump run, and the same problem was back! No OIL/BATT lamps with key "ON", Engine starts fine (so I have good remaining battery voltage) and BATT light stays on when running.
I cleaned the connections once, and thought I'd fixed it. What should I do or check next?

[xboxrox]

Congrats on getting the truck Maxedoubt ~ I don't have the answers you need but someone here does... I know that the brake warning light comes on if the brake fluid gets low... I had to replace the oil pressure sending unit to extinguish that light... I lived in South Everett over twenty years member FMS88 lives in Seattle and he really knows a lot about these trucks... You could PM him to see if he has the answer...