Neil, the Ford AM/FM radios from the 1970's are a bolt in. I have a 1978 radio that looks really close on the face plate. The only real tell tale sign is the slider bar for speaker balance, and a couple of other smaller details that are noticeable when side by side to the original.
I have heard that the 1971-? AM/FM's even have the same wiring connectors.
The one that I have has different wire connectors.
The only this is that if you have a console, the shafts may be a tad too short.