1950 Chevy Truck Rocker Panel

[rbarr4]

I am working on my first project truck a 1950 Chevy. Currently working on the cab sheet metal. I don't have any rockers panels in my cab, they had been cut off prior to my purchasing it. I have purchased new rocker replacement panels from Classic industries.

I removed a lip of metal from behind the lip of the floor panels that I believe were what was left of the original rocker panels. This tells me the rocker panels sit behind the lip of the floor panels. Kinda of a question since I have nothing to go by. My issue is I need to locate the new panels front to back on the floor panel. Don't have any reference of where that should be. The panel also seems like it could be tool long. How do I Properly locate these panels? FYI I also have the inner cab corner cut out of the cab at this time.

Thanks for any help or reference you can supply!