A New Genuine Meyer Plow Pump Angling Block Allen Bolt # 21826. It is part # 78 in the breakdown below. This Allen bolt uses 1/4" Allen it is 5/16"x1.5.
If you have a non-power angle pump then it is a shorter allen part # 21859.
This fits the E-47, E-57 , E60, E61, E68, E88, V66 pumps.
Make sure you also pick up a basic seal kit, the Genuine Meyer fluid you need, and the Meyer yellow paint to do a proper rebuild. If you are doing this yourself, below we have links to the service manuals to walk you through the rebuild.