Finding 360 engine/tranny to replace slant six

The thing with tunnel mods is the OD automatic, A518 or whatever. It's fatter in the rear area. You could use either a 904 or 727, with appropriate driveshaft

Not clear to me.......you interested in LA or Magnum or either?

The newer the magnums get, the more problems there seems to be in using original ECUs, one I've read about is security communications between key/ switch and ECU. I understand "there are" outfits that can flash the ECU to clear that IF you have proof of ownership, or so I've read. Someone above suggested Megasquirt, and there are other aftermarket injection systems, some of which could be adapted to "most" of the hardware you have now.

So let's say you find a late model magnum but with an OD auto, so now you need to scrounge up an earlier "non" OD automatic. My understanding that adapting the late engines to early torqueflites are these:

Some early torqueflites will have weighted converters for use with such as 360LA. 5.9 magnums are also externally balanced but they are a DIFFERENT weight balance.

This would mean (example) you'd have to knock the weights off the converter.....not difficult....

and use the factory flex plate, WHICH HAS the crank pickup teeth on it for multiport EFI, and then you'd have to cut a slot in the early TF bell to accomodate the crank pickup, also not difficult. AND at some point the bolt pattern for the converter was changed, so you might have to elongate one hole in the late flex

Also keep in mind that a 4x4 transmission does you little good, unless you can get a 2x4 core to swap the tail / mainshaft

There "are a few" motorhomes which use a weird short shaft torqueflite with attached emergency brake drum. Same deal as 4x4 trans, above. You'd need to get a long shaft core to swap out the tail housing and mainshaft.