My 62 Valiant

The reason why i was thinking it was aftermarket is because it was something that you could stick on the window, it still has the sticky mark on the window and has the lines going across.

Yep, definitely aftermarket.

The seat belts actually say Chrysler corporation on them. so does that mean they are the factory option?

Or dealer-installed, yes. (It also means they're old enough to be even more worthless as life safety devices than they originally were as lap-only belts.)