You need those parts, but some are diff lengths, so make sure you have correct length. Measure from back of trans where tube bolts up and to the rear where it bolts up and see if in range. You WILL have to remove front metals and engine mounts to move it all ahead enough to slip off the splines on your tractor and fit in the new parts. Mission has new gaskets for each end of the tube, or you can cut your own. Don't do w/out gaskets, it will slow leak. Silicone works, even leaving on the old paper gaskets if they stay together if you like that stuff, I don't. The coupler on back of rear trans will fit this shaft, but will need another small one like it to join the shaft to the rear of front trans. The one between trans now is a special two size in one coupler that you want to make sure you keep for re-install when fixed.
You don't say what is wrong with trans. Is it stuck in a gear? You can lift top off and re-position shifter into high gear and not move again and it will be like direct drive, same as the shaft. Just don't shift it. Have to remove the center console tin to get at the cover and bolts, but can be done with seat off and pulling hoses around and such.