Pretty certain I bought my locking cap from LMC Truck a few years back. Their current 2025 vol 1 CA 118 has locking vented gas cap on page 75. I attached pictures of mine and attempted to hold seal down to captures how it vents. Not real clear though.
1957 Chevy 3200 Daily Driver PS, A/C, Tilt column, Rebuilt 350, Rebuilt TH350, Reupholstered Bench Seat, sound proof/insulated, LED headlights/taillights/backup lights/interior courtesy lights. Follow in the DITY
