If you're going for a Concours type restoration, then yes.
If you're driving it and showing at local shows and cruise-ins than keep what you have. Nobody will know the difference.
I hadn't heard about the chance the solid transmission linkage could jam until
@cosgig mentioned it above. I kept the original solid rod on my 5.9 build. Now I'm always going to be worried (Thanks Geoff, lol).
Sounds like you're safer with the slotted rod.
