I have a 485 with a loader, set up same as your 484. I have had it about 20yrs, and it has been a good tractor, put about 2800hrs on it, has @3900hrs now. I roll hay with it and feed with it, so I have had to replace the clutch. Also have had to replace the brake piston seals in the axles. I don't have any vibration in my engine though. I think it is louder than a 4 cylinder, but it runs smooth. If your vibration is something you can feel, I would look deeper into it. I have had 2 engines in my life that broke a crankshaft, but still ran. Also worked on a 584(4cyl that broke its balancer-but your engine does not have that). Also have had clutch problems that caused vibration. Not saying you have a problem, but I would dive deeper. Good luck, Mark.
I'll look into it more. I might even post a video on here when it does it.
I agree on no balancing shafts or harmonic balancer, just a pulley on the crank.
Not sure what all to check. It starts and runs well. I guess I could inspect flywheel and clutch, but pushing in and releasing clutch makes no difference. So I don't think it is related to transmission. Actually considered taking the fan and belt off and running it to see if that makes a difference.