1963 Panoramic View slider back to one piece?

[MoFire]

Question for those who know, I’m looking at possibly purchasing a ‘63 C10 with what I think is an aftermarket split sliding rear window. Clearly these weren’t an option in 1963? So my question is, were any cuts made to the rear sheet metal to accommodate these aftermarket split windows? Or can I easily replace the split for a stock one piece glass window again?
I’ll add some pics for demonstration these aren’t my trucks.

Thanks!