I've got a real answer for this thread. I bought my car in November of 2012 so I was an early adopter (and paid a premium for that!) and had the 23Kwh battery. When the car was new I regular showed 78 miles of range. In November 2018 with just shy of 45,000 miles on the car (by this time my range had gone down to a shown 68 miles so I lost 12% of my battery capacity after 45k miles) it threw the yellow wrench warning light then shortly thereafter threw the "pull over somewhere safe" warning and refused to run. Had it towed to my dealer and then when I got home I noticed a small pool of coolant on my garage floor. I let the tech know about the coolant and sure enough, they found the upper battery was leaking. Ford approved replacement of both the upper and lower battery units.
After 29 days in the shop my car sent me a text message saying it had thrown a fault code so I knew they were finally working on the car. When I got up in the morning I had a text message from the car saying it was fully charged so I logged into the app and was elated to see that I was showing 102 miles of range! It is quite clear that the replacements battery packs are the 33.5Kwh version (the receipt shows the part number H1FZ-10B759-J for the replacement battery combo so last letter different than posted above). The car is in near perfect shape and now it has 100 miles of range. I am super happy.
The battery replacement, along with the door latch and 110v charging cord recalls, came to a total of $21,000+USD. Thankfully it was covered under the 8-year/80,000-mile powertrain warranty. I am not sure what I would have done if Ford did not cover it. Look for a battery out of a junked car perhaps?
So long story short - yes the 33.5Kwh battery units are bolt-in replacements and use the same charger and it appears no software update needed.