what size electric fan?

I want to change to an electric fan on my '96 Tahoe. What would be the best size to go with? Also would like feedback from anyone who has done this conversion. Thanks

I just replaced my belt-driven fan on my 1995 Cheverolet 1500. I used two 16" fans from the auto part stores, and the relay has burned out because I bought the wrong equipment. The best thing to do is to buy from http://www.flex-a-lite.com/ this company was just recommended to me by a professional auto mechanic. They will help you select the proper equipment (probably a kit) and they will have instructions Im assuming. I suggest them because more than likely if you buy from auto part stores like I did, you will have to guess which equipment is right for your truck because no one at the auto part stores that I have been to are familiar with or have completed this project despite the fact that
they sell the equpipment