Step 8: My switch had a spacer that I removed to give me extra clearance. Measure the spacer + the amount of metal casing you trimmed off. You will need to trim that much off of the metal plunger.
This is important because the way my switch worked is:
Neutral/Forward gears and light off = plunger depressed
In Reverse and light on = no force on the plunger
So when we trimmed the switch and removed the spacer, this allow the plunger to "sit" further up into the transmission. To ensure that it functioned properly, we trimmed that much off the front of the plunger.
Step 9: Trim the plunger