problems starting

[6point0damn2004]

Ok, my truck is an '04 6.0, problem I'm having is when I go to start my truck the starter doesn't have the same sound. It sounds very labored and very slow starting. It doesn't have usual zip that it normally does. Last couple of days it has been that way, I thought maybe it's just attributed to the cold. So, it did it again second time I thought maybe it was the batteries, so I started it, drove to the Advanced Auto Parts and had both batteries tested. The both tested good. One battery had 842CCA and the other had 998CCA. So the batteries are good, so once again, I think maybe its just the cold. So, tonight I went to start it after work and the started once again sounded labored and slow for a couple turns and then all I got was a rapid clicking sound, went to turn it over again, now all just rapid clicking sounds. So, my buddy I work with brought his truck over, hooked up the jumper cables and left his truck running. Went to start mine, same thing. let it sit for a little bit, starter sounded labored again but then again went back to clicking. So, we used the cigarette rule, you hook up the battery and smoke a cigarette and by the time you're done smoking a cigarette there should be enough juice to start it. So, it worked, let it sit while his truck was running and when he was done, went to start it and it turned over and then started. Also, if you turn it off and start it right back up, the starter starts like normal. It's just after sitting for a while that it has the problem.

SO, I'm thinking it could be my alternator, but I'm not sure. Any thoughts would be nice, what is the problem?

I just went and started it back up, I've been home from work for an hour it started right up. Could it be the starter freezing up?

ALSO, the other thing is the I think the bearings on the alternator were squeaking, which i know can be a sign of bad alternator.

Thank you in advance.