$450 of IPD brake parts later, and Helga running and stopping so much better...cheating a bit here...my other ride and workhorse, '91 Chevy pickup with uber miles...when lights on, dash and headlights seem a bit dimmer than they should be...not running, battery at 12.3 volts...while running, 'only' 13.8 going to battery, and screwdriver to the back of the alternator magnetic force test yields a weak at best magnetic pull to said screwdriver...time to replace?...alternator a NAPA rebuild I put in at least 3/4 yrs ago...haven't had any issue with startup, but....hate having go south on me in the middle of the occasional long road trip I use the truck for...

Before you spring for an alternator, check for a loose/slipping belt and
clean up the battery posts and cable ends, including grounds. Pay attention to the
crimp-on cable ends that can get corroded and resistive.
The D+ wire to the alternator needs to be solid too.

12.3 volts sounds too low for the battery, It should be 12.6, can you check with another meter? If the starter spins fine, maybe the meter is off? This will
throw a curve ball at diagnosing electrical issues.

You can check the specific gravity of the electrolyte in each cell to see if
your battery is in old age and nearing retirement time.

Does the truck have a separate voltage regulator? or built in VR module?
Look at that before replacing the alternator.

Happy holidays, Bill

belt tight...recent replacement with tensioner...terminals clean....I'm pretty good about paying attention to those..meter used was a good Fluke inherited from dad..have another, not as good one I have a go with...battery 3-4 yrs old, but a reputable brand...maybe electrolyte a bit low, will have to look...

thanks for you input Bill, and happy holidays to you and yours as well!

Tom