Vibration and rattling noise when decelerating

I’ll be doing 23 or 24 mph and take my foot off the gas pedal and I’ll hear/feel a vibrating noise until I get to about 10 mph. Sounds like it’s coming from underneath the car. Anybody ever run into this?

Start by replacing the rubber bumper in your motor coupling. Next step is replacing the transmission input shaft assembly because of worn splines.

And add a good quality grease to the input shaft

I just watched a video of a new motor install, in which he removed (what I think was) the rubber bumper in the motor coupling. It’s at the 8:15 mark. Is this what you mean?

Yes he was pushing the bumper into place in the coupling.

In a message dated 4/30/2020 9:28:53 AM Eastern Standard Time, writes:

Do you have a website for the input shaft repair kit? I have replaced the bumper and it worked for a couple of weeks now it has come back with a vengance
Thanks Bill