[69camarox]

hi can anyone tell me what this hole in the firewall is for ??

thanks Bruce

[LPete]

I think that's where the vacuum harness for the hidden headlights goes through.

[Forrest]

Also on 70 and earlier there is a orange "pigtail" power supply that runs from the fuse block thru the hole to the horn relay

[gto4evr]

Also where the cruise speedo cable goes through. basically an accessory access hole. Not all the bodies had them, when I added cruise to my 71, there's no hole in the metal there. My 69 convertible had the hole with a rubber grommet plugging it up since the car didn't have any of those options on it.

[69camarox]

ok. was wondering if that was the hole that my hood tach light wire went through the firewall??

wiring to horn relay makes sense

does not have hidaways or cruise

[motorcitymusclecar]

That hole in the firewall was used to run accessories as stated above. If you had Hide-a-ways it got the 3 hole plug - that is used for the vacuum hoses and if you had a hood tach it got a single hole plug for the tach wire. If the car had none of these options there was no hole. So if adding option you will have to drill it - I believe it is 1" and there is a locating dimple on the firewall to find the center. here is a picure of the three hole grommet. So yes your hood tach wire goes through that hole but not the horn relay that is part of the engine harness.