vibration problem

I have a 2004 Express van, 1500 with the V6. 5500 miles. Had it in a few months ago for warranty service for a leaking front cover gasket and leaking power booster unit. Since I got it back there has been an engine or transmission vibration, most noticeable as I come to a stop, but generally present at all times. I'd prefer to deal with this myself as I use the van for work and would rather not give it up to the tender mercies of the dealer.
The vibration seems to be increasing incrementally. No SES light displayed. It's possible that the new situation is not directly related to the repair and is coincidental to it.
Any thoughts about likely causes would be most appreciated.

Engine or drive train vibe, 5,500 miles? Make sure the driveshaft was not bent or kinked as a result of being lifted, seen that a few times.

Vibe at 5500 miles? Yup. No visible damage to shaft and the problem is not speed related per se. It almost feels like the OD is not disengaging, but driving then coming to a stop in 3rd seems to make no difference.