Really man you need to spend some more time looking around here and not be lazy.
I am pretty new here and in a few hours of going through threads I found the answers you are looking for.
Fans: new from any one of a hundred parts websites, or used from a junkyard. (still too new to even know what years) but if I needed to know I would at least look at a couple pages of threads to try to find out.
Harness: same threads as fans. Find a used truck and rob the harness. OR in every thread I have seen fans mentioned the BB harness has been mentioned.
Tune: dude seriously. Every thread I have seen arounnd here mentioning fans, tune, whatever everyone mentions Blackbear. Have you even read any previous threads???
Sorry if this seems too harsh but I am just trying to help you learn how to get the most from forums such as this.
If you want to get the most out of them you are going to have to look for the answers rather than ask a question that has been answered thousands of times.
On this page is an answer to the harness questions
http://www.blackbearperformance.com/services.asp
Here is someone who I'm sure would love to help you find a harness, a tune, and might even be willing to talk to you about fans. Jennabear chimes in on damn near every thread involving tunes for our trucks. If you have tune questions. BB is a great place to look and used by many
http://tahoeyukonforum.com/forum/member.php?u=132
Please try to look around for your answers.