I just finished putting a 3" body lift on an 83 K5 Blazer. It wasn't too hard but there is a few things to consider. Mine is a southern truck and therefore has VERY little rust. I was fortunate that all the body mount bolts came out with no problems. Northern trucks tend to have a lot of rust which makes removing the bolts quite a task.
If you have a trailer hitch mounted you may have to take that off to get access to the two rear most mounts. It depends on the type of hitch that you have. The portion of these mounts that are on the under side of the frame are held in place with brackets. If you are going to reuse the old body mounts this is no problem. If you are replacing the old rubber mounts (which I recommend) you'll have to remove the rear bumper and drop the rear portion of the gas tank to get to these mounts. Once again rusted bolts will make this hard. Use a lot of penetrating oil.
Your tranny shifter lever will need to be extended (the kit should have included a small piece to be welded in)
Also your transfer case shifter will need to be extended. This is not included. I used an appropriatly sized bolt and cut what I needed out of the unthreaded shoulder portion. This was welded into the portion connected to the T-case.
The fuel tank filler neck was just a little short for my comfort. I could have reused the stock tubes but I felt that there wasn't enough material overlap for the clamps. NAPA sells the fuel filler hose for 12.00.
If you have a tranny cooler keep an eye on those lines. I had previously modified my lines so I was OK. The OEM lines are solid and run iniside the frame from the tranny to the cooler and don't have any flex. You may have to cut the lines just before where they come out of the radiator to splice in some rubber hose. Make sure you get tranny hose.
The radiator hoses have enough flex in them to handle the lift.
Your brake lines coming out of the master cylinder have a spiral built into them and will expand on their own. Just keep an eye on them when lifting the driver side.
Also there is some electrical wiring on the driver side fire wall that drops down to the frame and goes to the rear of the truck that you need to keep an eye on. Check for other wires, most notibly the engine grounding strap which usually comes off the passenger exhaust manifold and connects to the firewall.
Your steering column will have to be extended. They come as a two piece shaft held together in a slip joint by plastic pins. Disconnect the shaft before you start the project. You wont be able to take the shaft out until you get the body lifted. Once out you can either drill out the plactic pins or use a torch to melt them out. Once out seperate the two shafts completely to clean them then reassemble. Once you put them back in I expanded them to the correct length and used a small hose clamp to keep the shaft from collapsing due to vibrations but loose enough to collapse under impact.
It is quite a bit of work even if everything comes apart easily. I did it in my driveway by myself over a three day period. It was my first time doing a body lift and was an eye opener. I could probably do another one in just 2 days.
Good luck. If you have any questions you can e-mail them to [email protected]