60-63 Suburban windshield/roof repair panels?

[EddC]

Hi all,
I'm fixing up the calamitous repair job to my '60 suburban but am falling short on information & detail. Mainly due to living in new Zealand, there is only a single 65 suburban that I've come across for comparison.
My '60 has had a pickup roof and a-pillars grafted on, some time ago. Not so much of an issue to fix up with a 64-66 burb roof panel.. but I'm struggling to get correct info on the differences between 60-63 & 64-66 suburbans around the a-pillars and inner roofs.

- is the windshield inner roof panel the same/broadly similar pre/post '63 - any pictures around of a 60-63?
- how does the area above the door differ between the earlier and later burbs? Same design or completely different?
- are there repair panels for the pre 63 trucks for the outer windshield to roof panels?
- do we know why GM decided to make the roof panel different between the pickup and suburbans? It's a small but very problematic difference 60 years later!

All help greatly appreciated.