New water pump 6 impellers whats up with that!

OK. I should have checked the service manual. You all that said use the 6 and the manual says 6 for AC cars and 8 for non-AC. You are correct. I looked at the specifications in the 1972 and it says six also. If anyone needs the manual it is available here on the forum. I’m guessing there is some reason why the AC and non-AC have different part numbers. I’ve seen both at Oreilly and they are visually different. Thanks for the discussion. Craig