I got this spot weld remover from harbor freight and was expecting it to be junk, but it actually worked really well.
It popped right off with a little chisel work:
Here it is removed:
After I got both rockers off, I drilled out the spot weld on the firewall lip.
Sometimes it may be hard to find the spot welds. I found that if you take a angle die grinder and lightly hit the area, the spot weld will show up for ya. Also, a little soap and water helps too.
After I got the spot welds drilled out on the firewall, I went in the cab and cleaned out all the factory seam sealer and started to separate the floor and the firewall. I made a slice with an angle grinder about an inch away from the seam. Then removed the remaining piece between the cut and the seam.
Again, this came out really easy. I hope Im not jinxing myself