85 Ford Bronco 4-Speed Automatic Clunking Noise Under Drivers Seat

I know this is not an automotive form or anything, but today I replaced the transmission mount on my 85 ford broco it has a 4-speed automatic transmission. Now for some reason the darn thing is making this weird clunking sound and it makes the driver seat vibrate. I'm sure I screwed up some where, but does anyone have any clue on what it might be?

Added (1). Also it is only doing it while driving in gear, I have not checked it in neutral as of yet.

You need more wiper fluid

The drive shaft for the front axle goes under the driver's seat. Turn the 4x4 function OFF and see if that helps to noise.

Sounds like the trans crossmember bolts to the frame may be loose on the drivers side… Check that. Have a friend start engine and shift the trans into gear and rev engine slightly /let out clutch with parking brake on or wheels chocked, bumper up against a tree or building, etc. To keep the truck from moving while you watch underneath the truck for any signs of crossmember moving or pinpoint noise/clunk.

Driveshaft u-joints that are seizing up cause vibration and noise. Pull the driveshaft and work the u-joints back and forth by hand. They shouldn't be hard to move. Mark the driveshaft and rear flange to make mating marks so you out it back in the same position.

Examine the nuts and bolts that hold the seat in place. Tighten them if they're loose. Replace broken parts.