check vehicles with carbureted engines if you go the wrecker on a quest.
mostly, what they are is a round plastic disc slightly larger that the intake tube. it is snapped on or screwed onto the front side of the air intake hole for the engine, it has some standoff legs to hols it off the rad support by an inch or possibly a little more. the air intake hose is connected directly behind it on the back side of the rad support. there is usually some sort of screen as well to keep birds and bugs out of the intake screen as well as the water and snow when driving. iy also keeps mice from crawling up the corrugated plastic tube to the actual air filter housing on top of the carb. so, the air intake is able to draw air in from the sides of the guard, where the standoff legs hold the solid shield away. I know the square body trucks had them.
here is a link to a used rad support for a mid 80's chevy truck. notice the part I am talking about next to the pass side headlight. another pic in the group shows the part sticking out the engine side of the support where the corrugated plastic tube would attach.
https://www.ebay.com/itm/Radiator-Su...edirect=mobile