Today I noticed that my voltage meter was staying on the low side of "normal". It has always been low when I first start up and then go staright down in the middle or a little towards the higher end of "Normal." At some times throughout driving today it would climb back up and then go down again. The battery light has not come on at all and I do not know how old the batteries are because I just got the truck a few months ago. Has anyone had a similar problem?

 

Yup. You need a new alternator. Or have yours rebuilt.

I bought a new Bosch and will rebuild my old OEM for a spare.
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I'd guess the alternator. If I were you, I'd go ahead and have it tested before I replaced it, just to be a little more sure. Also, my guess would be that you'll need new batteries before too long, anyway. That's what happened to me.

 

Check the 2 wire connector on top of the alternator. It gets usually gets crushed from laying on it while working in the engine bay, the spades and sockets can get loose. You may need to tweak the spades or squeeze the sockets a little tighter to get a better connection.

 

while you checking wires like cuda jim said to do check the hot and ground on the battery cables while you're there. I just found a 6 inch split in my ground on the driver's side when the ps hose blew the other day. It was from the corrosion that made it split. Just my 0.02

 

I also think its related to the alternator but If it goes and the batteries are the culprit, change BOTH at the same time.

 

It's always a good idea to check the batteries when replacing the alternator. A battery with internal issues with give a new alternator nothing but a short life. There's no substitute for a good old-fashioned load test.