I don't have the inside scoop on this, but I believe the ribbed type is correct. This is based on underhood pictures of Chevelles when new. It likely depends on which plant built the car and what was available. Pontiacs tended to have the GM-stamped hoses (Terrytown NJ & Lordstown OH). My neighbor has a'72 Lemans built on Pontiac MI with original(!) hoses & clamps and they are ribbed. Who really knows? I'd side with the ribbed items.
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