Did you miss one of my previous posts?
I said '93-'96 truck transmissions will work. Up until '96 Ford used the 302 and 351 in their trucks. '97 was the first year of the Modular engines in the trucks.
Also, I'm not sure on the length. I do know for a fact that the regular AOD truck transmissions are shorter than the Lincoln car transmissions, and the Mustangs ones are shorter than the Lincolns. So, maybe Ford kept that same thing going and kept the truck 4R transmissions the same or close to the same length as the Mustang ones.