Welcome to the forum
That is a really nice Suburban. It's not often you find a 4x4 let alone in that good of shape. Plus you got the original seats too!
Seeing this brings back some fond memories. My first Suburban was a white '63 4x4.
There should be a metal tag riveted on the drivers side kick panel that will tell you the original color and trim. There really isn't any way to determine whether these burbs originally came with a tailgate and hatch or the cargo doors.