Although not the least expensive option, you could go with a high output unit from the Mecahnical Man (mechman.com, I think). I've had one on my '01 2500 for 5 years without problem. I ran one on a Blazer for over 12 years without a problem I was very happy with that since I replace the NAPA unit every 11 month. Yes, NAPA would exchange them free under warranty, but they won't drive 150 miles north of Fairbanks at -45F to replace it for you when your truck is on side of the road. Two alternators from Mechanical Man, Zero problems.