I have a mid 70s 300 six. i bought it in pieces, so i don't know much about it. i need a crank pulley - one that i can run an alternator, fan and power steering pump. i am going to put it in a 65-66 or a mid seventies F1 truck, so i don't know which steering pump i will have. i understand there are more than one crank pulley for these years, but they all have 3 grooves. how can i find out the differences? how do i make sure i get the correct one? I value your opinions. Thanks to all. ...jack