1976 Bench Seat Cover Question

[72 Cheyenne K20]

I just bought a 1976 GMC K15 High Sierra and took the bench seat out to see if there may be any factory paperwork underneath. I can see that the original seat cover has been replaced but wanted to ask if the original bench would have had material in the back and on the bottom of the seat.

I can remember seeing material there in past trucks IÂ’ve owned and only remember usually being able to see seat springs.

Let me know what you guys think.

Thanks Scott