[Bruce Parker (RIP)]

Unless your Chev is before serial 484449999 modified to operate in the Owen Sound snow belt, in which case the parts books calls for:

4296310 Grommets, special, anti-snow, window flap securing (skagfeld pattern). Qty. 10

4296312A Seatings, fur lined, anti-snow, window flap securing (skagfeld pattern). Qty. 10

Say, I have a spare set of NOS ones just for you...

Ford CMP's never had these. Anything cold that could enter the cab and cool the engine down so it would run was not prevented.