I claim the ornamental design for the fluid end block for a reciprocating pump, as shown and described.
FIG. 1 is a perspective view of the front, top, and right side of the fluid end block for a reciprocating pump showing an embodiment of the design of my invention;
FIG. 2 is a right side view of the fluid end block for a reciprocating pump of FIG. 1.
FIG. 3 is a left side view of the fluid end block for a reciprocating pump of FIG. 1.
FIG. 4 is a top view of the fluid end block for a reciprocating pump of FIG. 1.
FIG. 5 is a bottom view of the fluid end block for a reciprocating pump of FIG. 1.
FIG. 6 is a front elevational view of the fluid end block for a reciprocating pump of FIG. 1; and,
FIG. 7 is a rear elevational view of the fluid end block for a reciprocating pump of FIG. 1.
The broken lines in FIG. 7 are included for the purpose of illustrating portions of the fluid end block for a reciprocating pump that form no part of the claimed design.