Have a 5 year old 17HP 42" Murray rider.
Model # 42571x8A.
Engine is model #42A707 Type 2653 E1

So far, I have replaced the battery, starter, solenoid, ignition switch, spark plugs, choke cable and rebuilt the carb and fuel pump. Also wire-brushed and cleaned all connections, etc. Shear pin is fine.

Mower still won't start. Cranks all day, but won't fire. No spark. Is it the coil? I don't want to replace another part if it is not bad. Where to I go from here?

Remove the blower housing, and you will find the coil, remove the smaller black "kill" wire from the coil. Then attempt to start the engine. If it started, the small wire you disconnected has a bare spot somewhere grounding to the engine housing somewhere. If it did not start, then the coil is probably bad.