Need advice on a purchase

[gordyzx9r]

Well, here is my first post. I'm in need of a truck to tow a '24 to 26' enclosed car trailer. I've always been partial to GMC and figure I would need a 2500 series. I've been looking at different years and I saw a beautiful black '00 on ebay. I've seen a couple '01's I like as well. I'm definitely buying used, I figure '00 would be the oldest model I would accept.

Are there certain things to look out for on these trucks?

Are there any kind of odd idiosyncrasies I should look out for from year to year (say '00 to '04)?

Which options should I be on the lookout for (especially concerning that I want this thing for towing)?

And lastly what kind of prices are reasonable for these?

I've attached a pic of the '00 I saw on ebay, man that's a beautiful rig (I think it went for a little over $15K).