The butcher will know what you want - or if you you are buying ready-cut in the supermarket, I buy a boiling ham joint, it's not as specific as you are asking.
Boiled in coca-cola - absolutely delicious and moist!
boxtops, you can boil any joint of bacon. It does not become ham until it is cooked. Shank is from the gammon and the hock is off the forequarter joint