…. Threw a battery in it this morning… seemed to do the trick

Glad you got it fixed.

… probably get called out again tonight lol

A new fully charged battery will work. But if it dies again , you have a charging system issue. A fresh battery will last an hour to an hour and a half or even two hours depending on vehicle. This is based on run time , as the engine takes power out of the battery without replacing it. If you put a volt meter on the battery while it is running, you should get 13.5 vdc to 14.5 vdc. If lower than 12 vdc , you have a problem.

A lot of alternators now have the regulators built in , not a separate part like years ago. Replace as an assembly.

Sadly too , replacing brushes in newer alternators is next to impossible. Wish they all still had the option like in Paul's truck.

Savell, don't wait for the new battery to run down in order to figure out you need an alternator. Just start the truck, then with it running, disconnect one of the battery cables. If the engine dies, your charging system (alternator/regulator/etc) is not functioning. Letting him drive around like this will just stress the new battery and get you called out again at an inconvenient time.

If it the engine keeps running with the battery disconnected, the alternator is working at least partially. It doesn't guarantee its completely trouble free though.

Think of this test as telling you either: its definately broke, or its probably ok.