Well if you look at page 8 in the upfitters guide for the E-350 stripped chassis:
https://www.fleet.ford.com/truckbbas...iring_v1-0.pdf
The left diagram has the plug for the wiper connections if you desire to wire up the stalk.
I think the owner's manual is just the manual for an E-350 (e.g. the full van) and thus does mention the switch. The Thor owner's manual is generic junk.