Floats,
Most likely it is one or two bad roller bearings inside the cluster gear.
See this thread ....
Even though this thread is about Mitchell Synchro transmissions I have had same problem with a rebuilt stock one. They use same bearings .
https://www.fordbarn.com/forum/showt...39#post1572639
See post 26 by Zener242 as he posted photos of the bad bearings from his Mitchell.
Also see my post #30 about the stock transmission that I built which failed the same way.
Noise is VERY LOUD and irritating !!!
It started out that it was a liveable level if I shifted into third at 20 MPH but it got louder as time went along.
If I pushed it up past 30 - 35 in second it got somewhat "quieter".