question about door interchangability

[Clancy68]

I have a pair of 68 doors off my old cab, and the cab I am loking at getting is a 72. I figured they would fit just fine, becuase all of the front clips interchange. but i read some where, (I don't remeber where) that 68 doors are different than 72. it is just the interior panel thats different? or are they shaped different and incompatable?

Thanks

--Scott