Its got the round hole in it, not the J hook like on car’s, right?
Take the blade off, bring it with you to a trucking supply store. Ask them for the wiper blade for a Ford L series truck. Then use your current blade to double check the size and mounting hole.
Truck parts store! That's the ticket. When I replaced mine (I brought in the blade assembly)....the guy wanted to know if it was a replacement for a Freightliner!