Jake53,
Without a hydrometer and a load tester, troubleshooting a battery is tough. They are a consumable..usually four years of life and they croak.
You seem to have a real good mechanical sense, carry on and you will figure it out.
My only concern would be the amount of charge..it seems quite high to me. If you have a spare, it would be fun to try and adjust the one on the rig now.
Enjoyment is the name of the game with these old trucks.
Stuart
