I don't really know if this is worth posting about. The solution seems rather obvious, but just in case someone find this useful, I'll post it anyhow.
This weekend, while in the midst of a 6-hour drive to the in-laws, the truck's ABS light started flashing. "Odd" I thought "I guess we'll have to get that fixed when we get back". Minutes later, the red battery indicator started flickering, and then went on solid. Oh crap. The voltage indicator was practically pinned on "L". Minutes after that, the dash went completely dark. No speed, no RPM, no lights, no nothing. But the truck was still running. Thank God we managed to make it a few more minutes to a parts store at the next exit.
After some conversation with the parts store employees and a physical inspection of the battery, it became pretty clear that the battery needed to be replaced. It was, according to the clerk, the original battery for that model. So the battery is/was about 6 years old. Some bulging had started to occur, possibly due to freezing. However, after some testing with the new battery in the truck, he was uncertain if the problem had been resolved, or if the alternator needed replacing. His suggestion was to drive around for an hour and see if the meter continues to drop. As I had quite a few hours ahead of me, and the next parts store was about an hour away, I figured we should just continue on our way.
Sure enough, about an hour out, it became evident that the battery was losing juice. After running around to a few parts stores, and yet again barely making to the final store (dash went black), I had a replacement alternator. Beleive it or not, an alternator is easy enough to replace. Assuming it's not crammed underneath the engine somewhere, or in an impossibly tight space, it's something that can be replaced in under a half hour with the right tools. You may need a metric wrench for some of the bolts involved. In my case, I needed a 13mm metric wrench for the mounting bolts. The socket for the positive connection nut was easy to find in the standard imperial sizes. Finally, and most importantly, you'll need a serpentine belt wrench. This tool has a square socket post on the end of a 2-3' flat-bar. This inserts into a spring-loaded tensioning arm with a pully on it, usually near the alternator. This arm keeps the belt tight, and the spring is quite strong. It's nearly impossible to move it without the serpentine wrench.
Anyhow, as I said, the repair is pretty straightforward. Once I had the proper tools, I was able to replace it in the parking lot of the parts store in about 30 minutes, and back on our way.