Along with the lock button location, which you can relocate if need be, having upper pads means no welding/body work if equipped?, you'll need to change out the glass and the rear glass tracks as they are different
Could you explain this? I'm not sure I understand.
You'll need to drill a new hole for the rod lock knob to protruded thru the upper sill on the door, as the 68 is located in the rear, and 69-70 is more forward, if you have upper upholstered door pads there's no need to weld up the unused hole, other wise if your car has no pads, you'll need to weld/body work the upper inner portion of the door panel
The 68 glass has a narrower glass runner than the 69-79, also the rear stainless rear trim on the side glass is different in shape/profile, assuming we are talking hardtop and not post model