Hudson Part Question

I can tell you.  It is a retaining clip for the wiper motor.  The left and right wiper towers (or "transmissions" which hold the wiper arms, are connected to the motor by steel arms (unlike the StepDowns, which used cables).  Each of the arms had a hole in it, and the hole fitted over steel studs which were welded to a short reciprocating bar on the back of the motor.  One stud held the steel arm (or linkage) for the right wiper.  The other stud held the arm for the left one.

Something had to hold each linkage to its studs, or it would come off the stud.  If that happened, the particular wiper would stop working.

Each of the teardrop-shaped gizmos slipped over the stud after the linkage had been slid onto the stud.  There was a tiny groove in each of the two studs.  The retaining clip would click into the groove on its particular stud.  The spring pulled both  teardrops together and the tension held them in place so they didn't come out of the groove.

SO:  lie on the floor of the car and shine a light up under the dashboard.  Find both linkage arms and fit the hole in each one, over the two studs on the pivoting bar on the back of the motor.  Then slide one of the teardrops over one stud, and the other over the other stud and push them over the stud until they click into place.  Your wipers are restored!

You can learn to grope up under the dash while sitting in the front seat, and put one of these clips on "blind".  Much easier than lying on the floor.

I don't know why this clip fell off in the first place, unless the spring has relaxed.  Actually, it looks to be in good tension.