So I recently got around to replacing my fan clutch which was half engaged all the time. after I put the new one on, I noticed the engine vibration at idle was a lot smoother, almost non-existent.

This truck sat for almost 6 years so possibly the fluid dried or sludged in one spot inside the clutch. I dunno how these things are designed internally.

Could a failed clutch cause vibrations if the fluid was dried out or am I just imagining it?

 

I would say yes that could happen or it was bent