I'm about to go through this whole process myself. My truck is 2WD 92 F350 E40D centurion 4 door extra cab.
I believe the planetary went KaBoink as I heard something (hard part) let loose under heavy acceleration.
Parts I have acquired are :
91 E40D 450 Super Duty w/parking brake.
92 zf5 idi
90 E40D Ambulance idi 2wd w/out brake supposedly good, but extremely nasty looking.
I don't have any specialty trans tools (what do I need specifically to gut my case for internals swap ?
Sorry for being such a newb, but as most.....I'm broke as a joke trying to get going again on a budget . I'm not intimidated by complexity getting inside the case
I assume I'll be forced to buy new internals as these most likely never received ford updates to avoid inevitable demise as all the rest of the E40D's tossed aside as boat anchors

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Thanks in advance
Any and all suggestions greatly appreciated.