I checked out the Ford battery specs not long ago. My 2019 (2552) flooded lead acid battery is still performing fine, but since I have really enjoyed the benefits of the AGM units in my house batteries, I'm interested in moving to a maintenance free (possibly AGM) unit for my vehicle battery as well.
My E-450 has the Group 65 from the factory. It is the Ford BXT-65-650 (650cca @ 0* battery). There are actually three different Ford batteries available in the Group 65 size with three different cold cranking amp ratings: BXT-65-650, BXT-65-750, and BXT-65-850--with 0* cca ratings from 650 to 850.
All sources for automotive batteries offer replacements for Group 65. I focused on the higher cca batteries (750 and 850) when looking at aftermarket units since I would rather upgrade the cranking amp capability when changing batteries. Maintenance free flooded lead acid units ranged from about $95 (for the Everstart Max at Wal-Mart) to about $160 (for the Autocraft Gold at Advance Auto and the Super Start Extreme at O'reilly's). Sam's Club, Costco, and many other suppliers also have sealed, maintenance-free 850cca units within those price ranges. AGM units are measurably costlier--$170 (for Sam's Club Duracell), $200 (for Advance Auto's Autocraft Platinum), and $240 for the Optima RedTop.