I can assume the alternator is tested as bad. I replaced mine because it was reading 13v with no load on it. When I got it out, there was a sticker that it was only SUPPOSED to be 13v, not 14.4v like most other vehicles i've dealt with. So if you're replacing it because it's 13v, save yourself the time, it's not broken. I put the new one in anyways.
Now, it is a pretty easy job. 2 long bolts hold it against the block, the tension is a screw. I removed the lower skid plate to get under, and the airbox to get at it from above. I didn't even have to jack the truck up, there was enough room for me to reach up. Took me about an hour total, I would consider myself more on the basic end of working on cars.
