5 required for both OM612 and OM647, five cylinder engines.
Existing glow plugs in your engine may be made by either Bosch or Beru. These are Beru/Borg Warner
Both are original equipment suppliers to Mercedes and are interchangeable with each other.
Beru is a wholly owned subsidiary of Borg Warner.
Sprinter 2002-2006 Do not try to remove glow plugs from a cold engine.
Before attempting to remove any glow plugs, start the engine and allow it to reach operating temperature. Failure to do so will probably result in shearing a glow plug off in the aluminum cylinder head. Before installing any new glow plug, coat the new glow plug threads with a good quality anti-seize compound, to facilitate easier removal in the future.