The 70 I have has a sheetmetal channel on both sides. Its about 4 inches wide and extends out as far as the bed rail. Screws in at the top and bottom. On the driver's side it covers just the fuel filler and main vent tubes. On the passenger side it covered 4 to 6 metal tubes that all looked like they were related to venting the tank and to return lines from the fuel pump (I think).This 70 was a plane jane rig with the utility buckets and no real interior except the back seat. My 72 parts (probably) Blazer does not have any of the same tubes coming up through the floor on the passenger side. Nothing there at all. On the driver's side It has a metal tube next to the filler tube that goes from the bedrail to the bed floor. So for all of that, I guess what I'm saying is you're right, they are different. I'll probably get some made. I want to run more than the stock two to use them as anchoring points for panels holding speakers and hiding things like an amp, some tools, etc.