[HO455]

After removing the air tank and the body mount bolts it was time to get the old wood out. The little piece in front passenger side corner only took a push and it fell right out. Then I screwed two wood blocks to the remaining big piece. (Photo #1). This allowed me to take the persuader and bump the wood towards the passenger side. (Photo #2) It all went fine until I came up against the rear tire. Curse those wide tires. Fortunately I had plenty of travel in the suspension and was able to jack the truck high enough so the plywood would slide over above the tire. Otherwise I would have had to remove the wheel.
The next step was to raise the drivers side up so the piece would then slide out of the back. Those GM engineers didn't leave a lot of extra room to get the floor out. The wood just fits at an angle through the back door/ hatch.
I wonder at what stage in the assembly process the wood was installed at the factory. It is hard to believe there was any cost savings for GM by using wood instead of a metal pan.
OK back on track. I used some wood clamps in the extend configuration (instead of compression) to push the wood upwards on the drivers side. (Photo #3) with them holding the wood I slowly wriggled the piece out the back, resetting the clamps a couple of times as I came out. As 04lsGTO said having friends would have made this much simpler. Finally success (Photo #4).