Late 70's sbc, pretty much stock. I am doing the head gaskets ans when i pulled the heads off (in the dark) i didnt realize the push rods are different. I am assuming they are 8 intake and 8 exhaust. 8 of them have the little groove around the tip and 8 do not. I guess the 350's i have owned in the past had after-market push rods because i dont remember them being different. Which ones are which? Any help would be greatly appreciated.