Are they same , ? I'm converting a 70 to non AC and have access to a 68 Non AC body tub, the vents and what not the same, anybody know for sure? I imagine they are but...
I know that the 71 body is different in the trunk rise area due to the fuel tank emission stuff, but unsure about 70 and back comparison. I see in NPD's Chevelle catalog that the 68 cowl/ dash area is listed separately, but then again, that IS for a Chevelle. With regards to the BUICKs, the trunk 'drop-off's' and tail sections are different, but that is obvious. I assume you are talking same body style (coupe to coupe; convert to convert; post to post; 4 door to 4 door), because each body style has its unique proportions, and will NOT fit the other body style...
I think he only is interested in the cowl . Just make sure what you use had the upper vents. Cheapo Slylarks had no upper vents.