Alternator/wiring problem?
 

Hey yall,
got a '97 1500, 5.9, and I'm having some weird alternator issue.
So, driving to lunch the other day the GEN light popped up on my dash, and I saw the battery meter had dropped down to 8 on the gauge.
I had just recently had the alternator tested, and it came back good, so I figured that there had to be a different issue.
I found that the positive battery terminal connector had a good bit of wiggle to it, and also, the clamp on the actual wires was loose. Tightened them both down, everything got back to normal and ran just fine.
The next day, sitting in traffic, the same thing happens; GEN light comes on and voltage drops.
I went to have the alternator tested, and it failed.
So, I got the new alternator, swapped it out, triple checked all the connections, and now it's still showing the GEN light and low battery voltage on the dash.
I'm pretty well stumped at this point.
one thing to note, is that none of the usual symptoms of a bad alternator are manifesting;
I drove it 15 miles across town when it last came on and it didn't die, infact it still had the same power.
no lights either interior or exterior dim or flicker at all when I start it up, and I've been able to start it just fine since this started, which was 4 days ago.
anyone have the slightest clue?

Start with checking the voltage at the battery and the alternator output with a handheld voltmeter. Compare to the dash gauge, that will tell you if it's a false alarm or if there is a problem with the alternator.

Also when you replaced the alternator how was the tension of the belt? They can stick causing the belt to slip.