You need to get one with same profile then cut to length.
The ones on my '86 Fifth Ave are extremely hard and L/F is broken. Five years ago (August 30, 2016), I pulled this part out and took a picture:
I need to get some myself, so if you find some, please let us know from where
and how much did you use (per door), please!
I would think this "should" be used by more than one car line.
BudW