I have a 88 D 150with a 318 and was noticing that the amp meter doesn't seem to move when I apply a load to the system, or turn things off. Also when the engine is off and I turn on the lights the meter doesn't move. It is showing over 14 volts at the battery while running. Just wondering if this is normal with the newer systems, I'm used to 60s and 70s Mopars where the meter jumps all over the place.

Your truck I believe should have a voltmeter. 13.7-14.7 volts while running is typically normal with automotive charging systems. Being an 1988 D-Series truck, I believe your computer should be regulating the voltage and not an external voltage regulator like you would find on earlier models.

It's a Amp meter.

Interesting. Just looked at the actual gauge. Looks like a shunt style gauge. Sorry for my misunderstanding, as that I figured Dodge would of switched over to voltmeter in the D-Series since Dakotas from that era used them and because of the different alternator and extra electronics for the Throttle Body Injection. On the 1988 D-series I've looked at I don't see the externally mounted voltage regulator on the firewall. If your truck still has the factory Throttle Body Injection and everything has been left stock then, the computer should regulate the voltage which is why you're not seeing the voltage drops or fluctuations that you're seeing. I will tell on the first year

1987 Dakotas they still had the old style alternator and external voltage regulator especially being the only year for the carburetor on a 3.9L V6. In 1988, they went to Throttle Body Injection and a different style alternator with no more firewall mounted voltage regulator. Your charging numbers are still within range and fine.

If they went to the shunt type meter one of my cars is the same, the needle always stays in the middle. I changed the guage with a known good one and checked all the wiring and could never figure out why.

My 87 had an amp gauge that didn't work or move with a bought it. I replaced it and worked find after that. Would show charging for a few seconds after starting and would move when applying and removing loads.