Provided is a manifold attachment assembly for attachment to a cryogenic cylinder. The assembly includes a knuckle configured to be attached to the cryogenic cylinder and a manifold configured to be attached to the knuckle. The manifold has an upper surface, a lower surface configured to abut an upper surface of the knuckle, a plurality of gas passages extending through the manifold for aligning with a corresponding one of a plurality of gas passages in the knuckle, and a plurality of valve seats in the upper surface each in communication with one of the plurality of gas passages in the manifold. The assembly also includes a plurality of valves respectively secured to the manifold in one of the plurality of valve seats. The attachment assembly provides a modular assembly that reduces refurbishment and requalification time, reduces assembly labor, and simplifies servicing.