The transmission could be the hard part. Not sure which AOD you've got, but tunnel and crossmember modifications would be necessary. Most of the ford AOD's are fairly small, so, tunnel mods would probably be fairly minor. But even small AOD's like the 200r4 still require modifying the original A-body upper crossmember, and of course a custom lower crossmember. There are conversion parts out there for the 200r4's now, but I haven't seen anything for a ford AOD.
Engine mounts by comparison are pretty easy. Other big issue would be headers, since once again you're on your own for this application.
The real question is, why is this in the "early A" forum? A '73 Duster is definitely not an "early A". :D
