1971 Cutlass 350, went to replace the thermostat today, and the AC Delco one I got does not have that tiny little arrow on it. Last time I did one years ago, you used the arrow to orient it towards the radiator (not like being upside down, but the clock orientation). The CSM even refers to it. I suspect it has to do with the flow, but are these new ones asymmetrical in how they operate?

 

Place open area towards front of engine. You'll be fined

 

Thanks, the replacement thermostat is open on both sides, so I just put it in with the open sides facing the engine/radiator.