The 69 AIM lists RH LH part numbers for 307 emblems.
The 396 car I am painting now has an original RH 396 Emblem which has the casting number of 3938672 RH and the Triangle TC logo inside the back, it also has a different profile than the other emblem on the car which has 3962951 casting number.
The NOS GM ones I see for sale have both 3938671 and 3962951 cast into the back.
Also I recently found a used RH version of the 350 emblem on ebay with the casting number being one off of the number cast in the back of the NOS emblems marketed as being for LH or RH.
So my question is were production line emblems different left to right?