The Stovebolt Site Forums The Shop Area Interiors Mystery Firewall Holes

I have a '58 3200 that I am reassembling. It was not complete when I bought the truck. I have the Factory Assembly Manual and can't find a couple of firewall holes. I have looked online and found other pictures of the holes but never with anything in them. I was hoping someone could shed a little light on what belongs in these mystery holes.

Here is a picture of the first set of holes (not my truck but the holes are the same).

The top hole (circled in red) had a rubber grommet in it like there was a cable going through it. The three lower holes (circled in green) had a small bracket mounted to it that also seems to clamp a cable to it. The alignment of the upper hole and the bracket seem like they would be perfect for the speedometer cable but in the Assembly Manual the cable is routed another direction.

Here is a picture of the second set of holes.

I have no clue on these ones. It looks like the dimmer switch holes but right next to the ballast resistor. There is no punch out in the inner firewall cover for these holes.

Any help on these is very greatly appreciated.

Chad

I took a look at my truck and the top hole of first photo had nothing and the top hole of the 3 had a plastic wire holder, such as the ones used for the wiring harness that runs along the LH inner fender. I would think the next 2 would have the wire holder in them if you ran the wire differently. The hole in the 2nd photo has nothing in it. I'd say it was put there for some sort of accessory your truck doesn't have, most likely a bigger truck might.

Thanks so much for looking. I have seen the holes in the second photo on a number of trucks but never with anything in them. I agree it is likely an accessory, I just wish I could figure out which one.

The lower hole has several uses, depending on model. It's primarily used for vacuum valves with either the hydravac power assist brake or the 2 speed axle option on Conventional cab models.
The upper hole is for the cable for the option overdrive transmission.

Thanks for the great info. Do you know if the holes were left open when the truck wasn't equipped with the options or were they plugged?

They were left open. The dash panel insulator would block off the holes from inside the cab.