I bought this 1996 Yukon September of 2007 with 142k miles on it. It ran great, was completely stock, and really didn't have any problems. I did have a leak in my coolant intake that needed fixing, so that was taken care of relatively quickly so I could install a block heater and get this thing started when it is -25 outside in the morning (and most of the rest of the day too for that matter).
I added an Air Raid intake to the engine in an attempt to boost milage and power a little bit. It did seem to help and it sounded cool. I'll see if the fuel economy is really altered once it warms up a bit. I also discovered the previous owner had installed an AstroStart remote starter/entry, so after a trip to the dealer for some new remotes I was surprised to have everything working.
I needed some new tires, mine were getting low on tread on and losing air. I made the decision to go with 285/75/16 BFG All Terrain KOs. In order to do this, I had a leveling kit consisting of torsion bar keys in the front and add-a-leaf springs in the back installed to give me a lift of about 2". The tires have been awesome in every condition I have encountered so far; snow, ice, mud, wet and dry pavement. I would highly recommend them. The ride after the lift resulted in a little stiffer feel, and reducing banking on the corners. A little sportier never hurt anything. I also put in some new Skyjacker 3" lift shocks and a Rancho steering stabilizer kit.
This is in good enough shape I am planning on making some further mods (some pretty major).
-Duramax/Allison 6-speed conversion
-14 bolt rear axle, I'll probably keep the 3.73, was considering a 3.42 but depending on how it drives with the new power train this might still be pretty good. I want to get 22-24 highway and still be able to tow 9,000 pounds. I am looking at getting the Dmax up to approx. 500 hp. Should be adequate for anything I could ever dream of doing. Will definitely perform better and get better mileage than the 5.7 in there now.
-5'' custom stainless exhaust
-Edge Juice tuner
-Maybe a new paint job. I had Saabs before and Viggen blue was always appealing.
-Dynamat sound insulation on the entire interior after being stripped down.
-Lower the front seats for a few more inches of headroom (I'm 6'6'').
-Add air cushions onto the rear springs to soften the ride a bit in back and help with towing and cargo loads.
-Add a billet grill and grill guard in front with a winch.
-LED tail lights and markers al around
Should be a lot of work and money, but once the snowy/cold season is here, I will be looking for an excuse to spend some more time in the shop. This should be a pretty nice/durable/economical/long lasting rig when everything is done.