Same as answer above, with one caveat... if you bought an alternator for a 69 and have the wiring / VR for a later model, the alternator would be wired different inside as 67dart273 mentioned. the 69 alt would be wired for 1 field wire vs 2 for the later electronic VR cars.
your title says "Amp gauge maxed out" now you are quoting voltages. if you AMP gauge is pinned to the right there is a lot of charging going on. If the voltage is 14.5 the voltage regulator is doing its job but still do as 67Dart273 mentioned about removing wires and testing.
have your felt the large wire bundle on the right side of the steering column behind where the key would be on a 67 or 68 (IIRC 69 is in the column)
Recently I drained my 67 Dart's 3 year old battery to the point it would just click. when I jumped it, it fired up but the amp gauge was all the way to the right, max charging. I drove it around for about 45 minutes and it stayed there. typically apon first start for a while it will go to the first bar to the right and in 5-10 minutes be back at center. I assumed that I had a problem and was ready to dive into battery, alt, VR, wiring, etc. then I got the idea to put the battery on a charger overnight. next morning started it up and guess what, charge indicator was back to its normal self.
QUESTIONS...
Did the car originally have a newer style (electronic) VR?
have you fully charged the battery then driven.
have you had the battery tested
have you had the alternator tested
Have you had the charging system tested ( auto parts stores typically can do it)
my bet is the Alt is not correct for the VR as 67DArt273 is alluding to.
