Theres rough idle, and theres rough idle

Cope said
My custom drive shaft came with solid U joints as well. They said the same. Solid or nothing.
(Drive line services, Santa clara)

The rear u joint in my 64 Valiant is original and has the Chrysler number on it with the little bracket connecting the two caps together. It's 55 years old. No grease fitting and it is still very good.