Charging issue '70 Swinger

my duster has a new battery, alternator and voltage regulator. it shows a light discharge in gear but shows a charge while rpms are up and the gauge also fluctuates when the signals are being used. for my car, it is normal.my battery has never gone dead and the system is charging when i pull the + side cable off the battery.i have relays for my HID headlights and they never go dim or show a voltage drop beyond my "normal" discharge reading even in gear. those older gauges are very sensitive to voltage and the slightest fluctuation in voltage will usually register.it cranks right over even on the coldest of mornings.my gauge never shows a "centerline" charge reading.it is always moving.i have never had a problem with it. i have been running the same charging parts for the last two years. i dont know if this is even relative to your problem but there arent very many parts that can cause a draw in your charging system in these old cars outside of a short circuit somewhere. but as stated, you could have gotten a defective part, it happens a lot.if you have another old mopar that charges correctly. it is easy to weed out the most obvious parts first ie; alt,battery,VR. BAD GROUNDS have been a huge part of the problems i have had. i have had bad starter solenoids draw a current off of the charger system as well. just a thought.....