DENNY, THE WATER PUMP THAT I TOOK OFF MY 1953 ,216 ENGINE HAS THE SAME PART NUMBER 839403 ,HOWEVER IT HAS GM33 ISTEAD OF GM7.I ORDERED A REBUILT GM AND IT CAME WITH THE NUMBER GM7 JUST LIKE THE ONE YOU SHOW,DO YOU KNOW WHY THE DIFFERENT #S ALTHOUGH SAME PART #?THANK YOU,VINCE