KNOCK SENSOR
WE HAVE A VERY SIMILAR TRUCK.
YOUR KNOCK SENSOR SHOULD BE DIRECTLY IN FRONT OF THE STARTER, IT THREADS INTO THE SIDE OF THE BLOCK.
THE ONLY METHOD THAT I AM AWARE OF TO TEST IT IS:
-HOOK UP A TIMING LIGHT
-ENSURE YOUR TIMING IS CORRECT
-WHILE WATCHING THE TIMING, TAP ON THE BLOCK WITH SOMETHING METAL (TIMING SHOULD RETARD)
-IF NOT TAP HARDER

-IF IT STILL DOESNT RETARD, YOUR SENSOR IS PROBABLY BUNK
GOOD LUCK
-12 ga