Ammeter is making me nervous

Hey guys: Getting my '73 Plymouth ready to go on the road and something weird is going on. I have noticed my ammeter swings nearly all the way over to 40+ at anything over idle speeds. From my other A-bodies I know this is normal right after a start but the ammeter should settle down to just above halfway afterwards. This one isn't.

So, I got out my multimeter and did some testing with that. At the alternator stud I get 13.9V at idle. At the battery I get 13.0V. Speed the engine up to 2000 rpms and I get 15.5V at the alternator and 13.9V at the battery.

Observation #1- The above-idle voltage at the alternator seems high Observation #2- The voltage at the battery seems in line, but there is a big drop from what's coming out of the alternator to what's measured at the battery.

Observation #3- The alternator seemed hot to the touch after running about 10 minutes. The only changes are: I had to replace the battery because it partially failed. It would still start the car but just barely, so the charging system had to work hard to get it recharged. I also swapped voltage regulators which had no effect at all.

Everything is stock with 49,000 miles including the original alternator. I've only driven this about 30 miles in the last year so I don't know it's something I inherited or not So, what's to be believed here..ammeter, voltmeter or both?