The invention is directed to a divider block assembly made from one piece of material. Traditional divider blocks require modular sections so that piston alignment can be calibrated precisely. The current invention uses replaceable pistons and sleeves that are suitable for use at high fluid pressures. The use of these pistons also allows for a single, bodied, one-piece, metal divider body, rather than the conventional multiple block divider blocks, which allows for a more efficient manufacturing method and stronger, more reliable, and more efficient lubricant dispensing system. The use of any of these aspects separately can improve performance, and not all are required in every embodiment.