Anybody know what these holes are for?

[markeb01]

Just curious if anyone knows. I've never seen anything mounted in the holes in any factory service or owners manuals or handbooks. I've circled the factory snap plugs in the holes I'm asking about. I'm assuming they're for a big rig application, but haven't seen anything there either.

[padresag]

are they for the std heater
ron

[Bugeyev8]

I think they are for factory AC if I remember correct?

[LILRED66]

I believe the factory A/C controls had three pull knobs, at least the 4-5-6 Chevy truck factory A/C system does, but I am not sure about the GMC trucks or the '60-'63 model years.

[markeb01]

Thanks for the replies. I've never seen a 60 GMC with factory air, so perhaps that is the answer. The Chevy service manual does show a Cool Pack air conditioning system was available, but doesn't show the operating controls. I'm pretty sure the standard heater used the same plate at the deluxe model, but only had two levers instead of four. Thanks again.

[62gmc910]

I would go with A/C controls marks right on the 2 or 4 slides on the heater
Any big truck stuff that I have seen was mounted below the key in a separate pod Air or vaccum controls etc

[thepartsguy]

Maybe the power divider switch or the red and yellow air brake knobs?