+1 for a bolt on upgrade ! I have been playing around with the settings in EFILive, trying to lessen the effects of the fans turning on. With only one fan turning on at low speed it was enough to stress out my charging system, and almost kill the truck at idle.. As luck would have it, GM made 2 different options for alternators for the GMT800 trucks, a small frame and a large frame alternator (I wont get into specific model#s here)..
Of those two options, I had the weakest of the small frame option. My truck only had a 105amp alternator from the factory, and that was in 2003.. They also made a 145amp version for my year, but my truck was NOT equipped with it. They also made a larger frame alternator that is generally rated higher in amperages and an overall better alternator. I was going to get one of the larger framed alternators and upgrade the stator and internals to make it a higher amp unit, but I ended up stumbling on a HIGH AMP version For just a little bit more on Amazon than the parts themselves were going to cost me and there was no core charge !
Best of all, it was literally a plug and play setup. Unbolt old weaker unit, bolt in godzilla alternator and never look back. I also upgraded the charging wire from the small stocker to a 2 ga unit. Fortunately the unit I installed had an overdrive pulley installed that made up for the diameter difference, it left me just inside the 'acceptable' range on the tensioner, win win win !!
I found a test sticker on the unit saying it put out 100amp at idle and 253amps at full load. My volt gauge on the dash never drops below 14v and I can no longer tell when the fans cycle on/off. For $140/shipped from Amazon, I'd say it was a good mod.
