This is the big F 350. I'll check GVW, but it was a 5th wheel tow machine in it's former life. 4Dr and 4Wd and extended bed. ECM makes sense. I'll pull it and inspect. Sucks since I replaced it a little over a year ago.
I still recommend pulling codes from the EEC IV connector under the hood. Your engine sticker will note either EEC IV for OBD1 or EEC V for OBD2