So the smaller pulley came in today. I got it installed at lunch. Took about 30 mins. I had to remove the alternator, and tilt it upwards, so I could get the impact on the 15/16 nut to remove it. The new pulley is about maybe 1/8 of an inch wider then the OE pulley. I had our lead mechinest look at it, and give me his opinion. It's so little that we both agreed that it should be fine, so I installed it as it came. It's not a whole lot smaller than the OE pulley, but it should give me a few hundred RPMs more at idle, and that's what I'm looking for. I did not need a shorter belt. It also was a close enough fit, to have plenty of tention. Before, I used to have to fight to get the belt over the alternator pulley. Now I have some slack when I push the tentionor in to release the belt. So I did leave to go get my lunch after I finished reinstalling everything. All is good so far. Time will tell how well this mod works. I will repost in the future, with an update.