If you're on a trip and can find a NAPA store on your path I'd recommend a NAPA 130 amp alternator. They have a better than average rating for their parts, and you can usually find a NAPA store in every town if you should have any problems down the road.
The 130 amp is the heavy duty alternator. The 110 amp is the standard duty. If you make it back home and don't feel like using a NAPA part you can order something else from Rock Auto, but then warranty service becomes a bigger headache if you should ever need it.


-Mike


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FWIW, I use an Autozone brand alternator. It seems to crap out about every 3 years, the same time as my battery in the Florida heat. I buy good batteries - Duralast Gold (top of line with 3 yr warranty) and Duracell (from Sam's Club with 3 yr warranty). It seems like one must go bad and then kill the other. The alternator is super easy to change on these. I can pull it, exchange at Autozone (10 minute round trip), and install it in under 30 minutes. In the 14 years I've had my 2003, I've put in 4 batteries (2 each Duralast and Duracell) and changed the alternator with the last 3 batteries. It's almost a maintenance item I've come to accept, but I don't mind because it's easy and cheap - free alternator and the battery is free or highly prorated. I know we (consumers) can usually get better parts (last longer, but still end up failing) and better prices on the internet, but I've found a lot of value in the convenience of lifetime warranty and easy warranty exchanges with the years I'm keeping this truck.