Last weekend while leaving an event I gave the truck a quick 0-100 romp then proceeded home on the interstate. I notice the truck was running a tad leaner than usual but nothing alarming. About 25 miles down the road I notice the HID lights start flickering. Looked at the volt gauge and it was at ~12V but there was no battery light on the dic. The truck was still running fine so with only 5 miles left to my parent's house I decided to push it thru. Made it about 3 more miles till the lights go out. I pull over, leave the truck to go get the Tahoe and trailer to retrieve the truck. I tried cranking the truck but the battery was drained to the point the starter just clicked. The part I fine extremely odd is I never got a battery light on the dic even though the truck seemed to be running solely on battery to the point of nearly completely discharging it. When I got back to my house Sunday afternoon, I removed the battery, put it on the charger and luckily it fully recovered.

Fast forward to yesterday when I start trouble shooting the alternator. I ran all the tests presuming a bad voltage regulator or rectifier. Nope. I found no continuity thru the brushes so I presume bad brushes. Nope. Pulled the brushes off to get to the slip ring, no continuity thru the rotor. I completely disassemble the alternator to find a broken outer winding on the rotor as it wraps around the ear right out from the slip ring connection. I simply unwound one wrap of the winding, dogged it off on the ear and ran it up to the slip ring connection and soldered together. Reassembled, installed on the truck and seems to work better than before. I did a little internet research and evidently this is not a very common issue as I could not find a mention of it. I am just theorizing on what could have caused the failure where it was.
-Manufacturing defect that just lasted as long as it has (original 180K mile alternator)
-Extra engine bay heat from stainless headers and supercharger causing rotor windings to expand and tighten.
-Higher RPM. I shift out at 6500rpm. With OD crank and 2.5" alt pulley, alternator rotor is spinning ~21K rpm.

Pic of where the winding broke...

 

My guess is that a manufacturing flaw was introduced into the wire either from bad handling practices or damage during the production. It looks like a tooling mark -- the wire necks down to a thinner than normal diameter near the failure. Quite smoothly. Perhaps the smaller diameter wasn't durable enough to last the life of the product but strong enough to not break immediately.