I didn't know there was a difference in turn signal cams from 1972 to 1973, I snagged the 1973 cam from the car that was in Pick n Pull with intentions of putting it in my 1972, they are different, mine looks like the one in this pic.... The one from the 1973 is much longer, has a metal plate behind it and has contacts I would guess that get power from the bottom plate on the steering wheel, I can't see any way I can use the '73 one, I didn't know there was a difference.
Catalog does show 2 different types, I never did one of the newer ones, just the early ones. Dorman 49301 - 70-72 Dorman 49304 - 73-77
I know of a difference between a 71 and a 74. The emergency flasher switch sit deeper into the column on the 74.
When I did the one in my sons 73 Comet, I ended up using one from National Parts Depot for a 73 Mustang. It worked perfectly. I don't know about other years. Lee "THE MAV" Richart
Yup, 73 and up are different than the 70-72. There is no way to make the one you got work, unfortunately.