The hardest part was breaking loose the big nut on the driveshaft centerline. It took a 3/4" drive socket set and a 5' extension bar slid on the end of the breaker bar. I'm guessing at least 300 ft/lbs. That kind of torque almost ripped my vise right off the work bench.
Do the u-joints too as long as you have to drop the drive shaft. And put index marks on the shaft so it goes together the same way it came apart. Get things out of alignment and it can cause some hellacious vibrations.