Do a Google search for 'Absorbent Glass Mat Battery Transit Connect' and you'll find a link to the discussion here - You can't find a darned thing searching this forum
Anyway, it's a Sam's Club Duracell Group 48 AGM battery - $159.99 when we bought them in 2017. Another Google search gives the dimensions as 10.9 X 6.9 X 7.5 inches. Theres a spacer in the battery box to keep the little Ford battery from moving around and you have to remove that to get it to fit. It's taller too and barely fits, height wise.
I run an inverter I mounted in our TC to charge 2 Segways and I also use it to run an air compressor for filling tires. It's a great battery and has served me very well. I highly recommend it!
Hope this helps you
Don