Barracuda unibody year to year differences

Wondering if the 67-69 notchback unibodies are essentially the same part or if there were any changes. I know the 67s have the VIN on the driver door sill and the 68 and 69s have them on the dash pad, but otherwise are they the same? How about 68s and 69s?

I am looking to possibly replace a 68 with a new unibody and want to make sure it is as close to the same thing as possible. Wondering if anything other than a 68 would work.

Let me know if year makes a difference and if any options make a difference- auto vs. manual, for example, and fender light holes. More concerned with just the unibody, not the fenders, doors, trim, etc.