Doors: 76 vs 87

[Chevy1966]

I'm trying to understand if there is actually some difference in the internal door hardware after the '76 model year? I see various components listed for 77-87, but are these parts exactly the same for 73-76? I know the door panels are different, but what about the internal parts like vent windows, regulators, weatherstrip, etc.? Thanks for any help!

[bigblock73]

The regulator, inner door window tracks and handles are different. Learned the hard way when I put 77 up doors on my 73.

[motornut]

I used 89 parts in 78 doors.
78 doors use metal clips on the door rods,and 89 it's plastic clips,
and the (89)glass is thinner,
but other wise it's (89) glass,vents,seals,panels,inside handles,regulators/crank

[bigblock73]

77-87(91) doors shells are the same, and the parts that go in and on them interchange. 73-76 are unique to themselves.