I claim the ornamental design for a mounting rail and slot connector assembly, as shown and described.
FIG. 1 is a perspective of the mounting rail and slot connector assembly showing my new design;
FIG. 2 is a front view of the mounting rail and slot connector assembly;
FIG. 3 is a back view of the mounting rail and slot connector assembly;
FIG. 4 is a left side view of the mounting rail and slot connector assembly;
FIG. 5 is a right side view of the mounting rail and slot connector assembly;
FIG. 6 is a top view of the mounting rail and slot connector assembly; and,
FIG. 7 is a bottom view of the mounting rail and slot connector assembly.
The broken line showing of mounting rail and slot connector assembly is included for the purpose of illustrating unclaimed matter and forms no part of the claimed design.