It's probably because nobody can say for sure. In '72, the Rallye was a seperate VIN series, so they could track how many were produced. In '73 & '74, it became an option package only- no more seperate VIN. The code on the fender tag would be A57. If it would help your decision, however, the number of 340 cars built in '73 was 8435 out of the total production of 32,596.... that's if your car is a 340 (H code in the VIN). They did build Rallyes with 318's as well.