Michael's Resto

I just ordered the 1/2 rear quarter panels from Wolf Steel and I understand that the 78 year model may be different than the other year rear quarter panel. Can anyone tell me if there is significant difference that would produce a problem for my resto? The wolf panel references models 74-78 quarter panels but he is unsure if he has the correct panel to make and sell me. Please advise anyone that might know what if any the differences are. Thanks mlctubby