I have almost got a smoothed firewall. The last 3 holes are in the center of the tunnel and have square nuts welded inside the cab. Were these holes for the heater or what? I don't think I will need them but not for sure.
Thanks again.

 

Without checking mine I`d say this sounds like the Foot feed for the throttle linkage. Hopefully someone that knows for certain will jump in. I`ll check one of mine when I get the chance.

 

I'm thinkin Morris is right.... gas pedal linkage on my 53 is just off center toward driver side.

 

It is for the gas pedal linkage for certain.

 

no the 2 holes above those are for the factory gas pedal linkage. i think those are to mount the interior firewall insulation cardboard panel. mines alittle modified, but to 2 holes @ 6" aparts just above the rib above the 2 square'ish nuts..........