Far as I know from 72and up ralleys should be same-tach, gauages, clock, ac, etc. ( can't see any changes to the ac. part! )
differences would be for the seat belt system- 70 was different- but just don't worry about it- I have a 72 ralley dash in mine- only I used the seat belt light on the side- had a lens made up to say " LINE LOCK ON " and used it for the line lock indicator.
the delay timer was a acc. add on- not part of the main harness- there is connections for it. Acc. diagrams will show it.