Ok I learned this the hard way with my project. In 72 the D2AR casting case got a boss and a switch for seatbelt warning lamps. Anyway, this boss on the tranny case will not allow the 3/4 rod to clear for 3rd gear. Thus the revision to the 72 shift rod.
I found my solution through Bill the Hurst Shifter guru. I can now hit 3rd gear. Yes my car was not an original 4 speed , when collecting parts over the years I built up the D2AR case sin e it was the best I had . Didn't realize that the 70-71 Hurst shifter was a mismatch until test drive.
Kcmash