From this chart from my mopar the 273/318 manifolds are the same in 67 - 68, but seem to change casting numbers every couple of years...
However you need to question the accuracy of the information because if you look at the top three listings, they conflict with 2475719 being listed for 65 - 68 left side, then the next two listed below that say 2465857 for 64 - 66 left side for Dart/Barracuda with 1739599 being listed as right side for 64 - 66 Dart/Barracuda....
Unless the 2475719 being listed for 65 - 68 left side was used on other body styles in those years...
