The problem is in the pinion gear in the LU that drives the rear of F and R gears. That relationship has to be set to a specified gap (shims) and that takes a special tool..per the book. Course you could get a prop shaft and water pump impeller, and new seals for the top of the shaft and prop shaft and drain/vent plugs and hope for the best without checking the mesh dimension.
You have 3 options when you are finished. It won't work as it's binding. It is a sloppy and you have gear whine, or it works. Actually 4 which would be to take the LU to a mechanic with those tools and have him install the shaft and setup the mesh dimension.
Course before I did much of anything, I'd pull the LU and check the top of the shaft and look up at the socket in the bottom of the crank shaft and see that that interface looks ok. Then I'd crank the engine briefly (no water pumping), or you could have someone hold a garden hose at the inlet to the water tube in the mid section that attaches to the output of the water pump so that you can run it longer to ensure that you didn't throw a rod or something.
