Oil Pan Differences

The 66 needs a new oil pan gasket. While researching gaskets I found that some pans have ribbed rails while others have smooth rails regardless of sump location. Selecting the correct one piece gasket is determined by the style of pan.

My 1980 302 has a smooth rail pan which seems a bit weird since I thought early stuff was always ribbed rail.

I also noticed there are pan rail reinforcement bars available and wondered if these are stock or just an aftermarket item.

Are they required when using smooth rail pans?

Pic of a ribbed rail pan for reference

Attachment 22632

I think the distinction between smooth / ribbed rail gasket started with the aftermarket pan builders.
Pan reinforcement bars started with the OEM's, aftermarket was slow to the table.