Hopefully my experience might help someone down the road.

On Friday 6/18 I was cruising down the interstate I-10 heading west, in heavy traffic. AC blowing cold, tunes are on, but not super loud, everything is good in the FJ world. I drive through the downtown 'tunnel and out the other side, and about 2 miles past the I-17 interchange the dash lights up like Christmas.

Every dash light is on. Throttle still worked, brakes seemed to worked, so I started my journey to the shoulder. But a few lights turned off .. but others stayed on. Ok Ill keep near the shoulder and see if I can find a proper exit. I cruise all the way out to Avondale and park. Turn it off. Look under the hood and there is still everything there with no burnt smell or any leaks. Ok turn it back on.. slow to crank but comes alive.

Ok - replace battery (It was an Excide that was about 34 months old)
Nope - same behavior

Get a new alternator from Oriellys on Saturday 6/19 and swap it out in the driveway. Bingo! All happy.

Anyways there was no previous no warning signs no degraded performance from the alternator -- it just died. This is now my third alternator. I guess water crossings + desert grime (sand) is a bit harsh.

Aftermarket alternators are junk. They dont last. The OEM Denso typically only need the brushes replaced ($20ish). If a bearing or regulator/diode pack is failing you can get a reman Denso from Rockauto for $118 or upgrade to the 130A from a Tacoma for $122.