Core support/radiator support holes

[Harrison.]

Can someone help me identify a few of these holes? I'm filling un-needed holes and there area a handful I can't figure out. First off, there's a big hole right above the hole for the parking lamp on the passenger side :


Then on each side near the top there is this little 1/2" or so hole:



And finally there are two small 3/8" or so holes right at each corner of the opening for the radiator:


Do I need all of these? Thanks!

[Nomadicflyer]

Here's what they are on my truck. Your results may vary...

1972 C20

The hole with the beveled recess is for the parking/turn signal lights. View of both sides.

Upper corner of the radiator cut out is where I mount my transmission oil cooler. I'm not sure if that's for the AC condenser mount, or a shroud. Someone else will have to answer that.

Good luck!

[Harrison.]

Thanks! Looks like your truck isn't using that big hole near the pass side turn signal pigtail. I'm wondering if you're right, maybe for the AC?

Edit: I looked at the instructions for a vintage AC unit and it does appear that big hole is for the AC lines.

[B. W.]

The large hole is for the A/C lines, the four holes around the radiator opening are for the A/C condenser mounts.