Yep, a new electric wiper motor will fit, but it's real close. Your choke cable is going to rub it slightly, but not enough for any issues. I don't remember the cowl vent being an issue though.
I just finished a complete restore on a 51 3100, bought an new electric wiper motor from one of the vendors we all use (won't say who since it has stopped working). Although I installed mine before anything else went in under the dash, so I had room and could see everything. I'm dreading taking this one out.....cause the truck got finished....and it ain't empty under the dash anymore.
What you're pictures show looks like what came with mine.
