what exactly did you modify about the door panel to go on? you sure it was because the door is different and not just because the old door panels can be a PITA to get lined up properly, esp where they hang across the top edge?
it is my experience that there is nothing different about any door 79-93 except for mirror style and the belt molding. 79-86 mirrors are boxy, 87-93 are smoother, and mirrors are meant to fit the appropriate belt molding. i know this because i have put 92 doors on an 88. they are all the same.