On my firewall I have an oblong opening on the passengers side. It is about 3 inches long by an inch wide, near the heater.

I thought as I put the truck (1953 chevy 3100) together I would know what went there. It is not for my heater.

Any idea?

My setup is just like this. Maybe it was for a different type of heater
Hole in firewall

Last edited by BSCowboy; 06/25/2013 8:40 PM.