Need some insight installing a rear wiper motor assembly

[Tinker]

I had to replace the rear window in my Suburban.

It was due, as the defrost was pretty much T/U, but I hastened its demise last weekend by smashing it with a rock so I could get into the locked truck after a backcountry canoe trip.

Now I'm re-installing the rear wiper motor assembly and I can't figure out how to detach the post/cap which should fit through the lower R hole in the rear glass. Surely it comes apart; there's a bolt on the inside of the housing that mounts the motor to the plastic and to the window. The bold head and the plastic cap both turn independently; but they just keep spinning. I'm reluctant to try prying since all the plastic is a bit brittle. Anyone had to do this? I've attached a picture for context.

 

[Tinker]

I was able to take the housing off and remove the bushing/stud assembly from the plastic mounting plate. I've included pictures below. The flange nut is machined to take a 7mm wrench at the base and is supposed to be held in place by a rectangular ABS collar on the mounting plate. The black cap is just plastic fused over the nut and is worthless for grasping. I had to cut open the mounting plate to get the shaft out and then I could get a wrench on it properly and disassemble it. Far from a good design; this one must have been handed off to a 3rd year engineering intern.

 

[MrMarty51]

Wow. That appears to be like some of the crap I run into.