I have 86 doge B250 van. Around 35- 40 mph power off I get a vibration . Last year I replace d a u-joint for a similar problem. Now I think the yoke out of the tranny might be bad. Has anyone changed this bushing before?

You replaced a u-joint, or both u-joints?

That's what I am trying to remember. If I did one or both. I think it was one. So naturally replacing the second one is on the list of possible solutions.

Yep, I'd start with that. If one was worn, the other probably wasn't too far behind it.