You are mistaken about the bumpers.
'60-'62 bumpers are different than '63-up bumpers.
Suburban rear bumpers are Suburban only, divided '60-'62 and '63-'66
Front suspension is '60-'62, '63-'66.
Rear suspensions are likewise divided.
Radiators are also '60-'62, '63-'66, along with core support and fan shrouds.
The panel that the grille mounts in is different as well, '60-'61, '62, and then I think '63-'66, but it's just a matter of a couple holes. I put a '60 grille in my '62, and don't remember if I had to drill extra holes or if it was a bolt-in.
Kick panel vents are also '60-'61, '62-'66.
-Brad
