I just read Rob Keeble's post on the repairs of his mini-van and it reminded me of the day back in the mid 80' I took my 1971 Chevy pickup that I "inherited" from my step-father by way of my half-sister and her husband... it had a 6 cylinder engine and it was time to renew the license plates... in Texas vehicles require "inspection" before they can be re-tagged. Drove down to the local inspection station, he looked it over, all was well, even though the column gear shift tended to drop out of the shift levers under the hood if you shifted too fast and to fix them I had drilled a hole in a rod, put a piece of coat hanger wire through the hold as a stop.. the body was rusted through under both doors, there was hole in the floor board under the seat big enough for a cat to go through.... the inspector said I needed an air return?
I said fine, where does it go.
He showed me a hole in the underside of the air intake that sat on top of the carburetor... here.
Okay where does it go from there?
Against the engine block.
Okay how does that get air back into the engine?
It doesn't matter, regulations from the state says you need one.
Okay, where do I get one?
I have them, they are $19.95... they're a flexible metal tube you can fit on the air intake and put the other end against the engine block.
Okay, how do I keep it from falling off and possibly getting into the fan blade or hanging on some other engine part moving?
That's not a problem, you can take it off after I've inspected the vehicle... it just needs to be there for the inspection. I can't inspect it without one.

I'm thinking he saw me coming and decided to add to his "sales" as the following year I went to another "inspector" and nothing was said about an air return... I had the one from last year in the glove box in case I needed it... then regs changes for the EPA exhaust exams and you got a rod stuck up your tail pipe....