The 3.9 4 cyl B would be same but easier on length than the 5.9 6 cyl. Around here we have Fords and Chevys running everywhere with the 5.9 Cummins B salvaged from the earlier and wrecked Dodges. They usually look for the 5 spds so they can swap tranny and all to not have any fit/adapter/clutch issues. I have a friend who is always buying dead gas duallys and good cummins engines, assembling them and selling for a tidy profit.
I just wanna be different... Thought about the 4-53 deal, but I've always wanted to put a DT360A International in my Chevy 4x4. I also think a 3126 Cat would be sweet, but alas, its all electronic, so it would be more than us shadetree'ers might want to tackle.
The most bizarre combo I've seen was a 3208 Caterpillar and Allison automatic shoehorned into a Chevy dually. They had to stretch the front end and raise the hood to get 'er in there.