Depends on "Supposed" definition in you post.
If your going to a true restoration as it was in the day then complete one piece no breaks. (not a line). Still available by some vendors.
Here is a reference from the shop manual
https://chevy.oldcarmanualproject.co...51ctsm0105.htm
Other vendors have done the "Line" type so they can do one part to fit multiple years and manufactures. Cut to fit. And there is nothing wrong with this type with proper sealing.