Take a marker (or scribe them) and mark each shaft at the yokes so they will go together the same way.
Line those marks up when going back together. This will help keep the balance.
Take out the bolts holding the hanger bearing to the chassis and let it down to the floor.
Take the rear u-bolts of the bearings at the rear end and be careful not to loose the bearing caps. Put tape around them to keep them in place.
Pull the driveshaft out of the transmission.
The shafts should slide apart at the hanger bearing.
This is the perfect time to replace the rest of the bearings, transmission and rear end seals too.
Clean the shafts off real good and grease before assembly.
You should be able to slide or press the bearing off and new one on and then reverse the steps for installing.