Here is a followup post with some photos and some additional thoughts. When I went to Baxter's Auto Parts, the OEM recommendation was 16" blade replacement for the rear. This is the same size I removed initially, the problem I had with the 16" wiper blade was hitting and scraping along the back of the window weather stripping and was causing a considerable gap in the wiper coverage leaving a good portion of the rear window obscured by what the blade would miss. I recall this clearly. I decided to get a blade that was slightly smaller than what was OEM recommended so I went with 15" blades.
Here are some additional photos.
My replacement wiper blade did not include a blade post so I had to carefully remove the rusted post from the old blade. I simply used a large set of pliers to gently persuade the rusty blade post off the old blade.
Seeing how rusty it was I cleaned up the rusty blade post with a little WD40 and a wire wheel to get any rust off of it that I could. I did a through job without damaging the blade post. However, I did notice a lot of pitting in the post and it might be a good idea to swipe these from a Gen 1 or even Gen 2 wiper the next time you are at the junk yard.
Once it was cleaned up a bit, I was able to insert it into my new wiper blade. As I pushed it gently into position, I noticed an audible "click" and I also felt it in my finger tips.
I reengaged the blade post back on the wiper arm very easily. Notice that the blade post has tapered ends to make it easy to slide this into place.
Once that was engaged, it was a simple matter of a gentle push to get this blade secured to the wiper arm. Pretty simple just took me a while to figure out the release mechanism.