Electrical Issues on my 65

[TLoz]

Hi,
I've got a 65, 3/4 ton with a few electical issues I need some advice on. I changed out the voltage regulator, battery and alternator-the system stopped charging and all were old. Now, it charges very little-as in if I use the lights or wipers the battery runs down. Last night I fully charged the battery and drove into work this am with only the lights on. After 40 miles the battery is dead. One interesting observation-the amp gage swings over to full charge during starter engagement. Any thoughts on what the problem may be? Thanks in advance. Tom