Why does my pump have so many letters on it. I know the 12jc and the A but what is the H for? Is the SS saying it came with a stainless impeller and shaft,because the pump does have both.Boat only runs 3800rpm so i think it has an A impeller.any ideas for the newbie? 455 +60 over olds torker intake eldelbrock 750 carb new comp cams 280 marine cam,