I think I had about 50 hours into mine the first time I did them. That was with the engine in the truck. I did not machine the heads the first time. I did spend a lot of time trying to clean the manifolds, intake ports, and y bridge by hand to get the soot off, that was a notable chunk of the 50 hours. I also made my own EGR blocker plates from 1/4" steel plate at the same time.
Definitely pull the cab if you have a lift, or pull the motor if you don't. I've done it with the engine in the truck, and with pulling the engine...will never do another set with the engine in again. Hopefully will never do another set period... :roflmao: