83 2001 Interior question

When I bought my boat quite a few years ago, the interior had already been replaced. It's time to redo it again and I'd like to return it to more of an original look. I started looking through some of the picture of other 83's and I notice some of them have different seats. Some have a swivel driver seat with a solid base under the passenger seat, and a split rear seat. Other ones have a solid plastic or fiber glass base under the driver seat and some metal brackets holding the passenger seats. Any ideas why the differences?

Mine has the swivel driver seat with the solid platform under the driver seat. Btw, the passenger seat also folds forward so you can get under the bow.