I just installed a zero rate kit on my 78 Blazer and I tell you it was a learning experience. Let me first answer your question. The center pin is long enough, too long actually that I had to cut the the center pin about 1/4 of an inch off to avoid hitting the u-bolt plate. Anyway going back to my experience. First, I painted the blocks with rusholeum to avoid rust from contaminating the bare metal. I started on the passenger side, pulled the passenger wheel off (BIG MISTAKE), I couldn't find a jack and/or jack stand long enough for my truck to get the weight out of the springs. I ended up placing a jack under the axle tube and jack stand under the frame. I then slowly lowered the jack (wheels off) to a point that the brake drum was almost touching the ground to get the weight off the spring. What a pain in the @ss. Finnally I got the spring out, bolted the zero rate using the center pin/bolt that came with the kit. I started puting the lift spring back on, mounted both ends of the spring and started jacking the axle up. The axle must have moved an inch backward. The spring center bolt wasn't lining up with the axle plate, it was an inch off!!! I tried pushing the the massive GM 14FF an inch forward by myselft to center it, almost broke my back to no avail. After several attemps, jacking the axle up and down etc.. it finnally lined up, wheew. After serveral hours, and almost drained out of strenght, I managed to get the passenger side block done. I still have the driver side to do next. So after a deep breath, I said to myself, there's no way I am going to go through the same challenges again. So I left the wheel on instead, yes wheel on and removed the ubolts. I then jacked up the spring (yes only the spring). As soon as I got enough clearance to remove the center pin/bolt, I placed a jack stand under the lift spring for safety (I like the idea of having 10 fingers). You will need a vice-grip or some sort to hold the pin from turning while you unscrew the retaining nut. Mine was so rusty, it took me a while and ended up cutting off the retaining nut using a grinder/cutting tool. Once the center pin was off, I simply bolted the new block using the new center pin that came with the kit, lowered the spring back to the axle, put the ubolt back on and wolla! I'm done!!! Remember, you may have to cut the center pin a bit short to avoid hitting the plate. Good luck and I hope you get a change to read this post before you actually do the work. Remember, you don't have to pull the wheels off and always use a jack stand. Enjoy and I am sure you'll have fun doing it. I did.
