The invention is a distribution block assembly that contains replaceable sleeves and pistons that are suitable for use at high fluid pressures. The conventional distribution block assembly can be altered to include end plugs and these replaceable sleeves having designated precise quantity of lubricant distribution so that the user can alter the distribution levels by changing the replaceable piston/sleeves and allowing for users to fix excessively worn pistons without having to dissemble the entire distribution block. The use of these piston/sleeve assemblies transforming conventional distribution blocks making them more versatile and reducing the costly expense of manually replacing of the entire distribution block.