I was able to get the fan belt on and not certain if it was the easiest method, but I'll share in the event it helps someone else in the future.
1. Removed mower deck.
2. Removed the two long bolts (12mm) that connect the drive shaft to the hydro unit. These are the bolts that go through the 2" long aluminum spacers. (12mm and something to keep motor/shaft from rotating)
3. Removed shaft from the motor side splines being careful not to damage the plastic disk (flex coupling) to the hydro unit during the process.
4. Removed the 4 (10mm) fan shroud bolts.
5. Loosened alternator (lower bolt 13mm and upper bolt 12mm used for adjustment)
6. It is very difficult to get the old belt through the lower (motor) pulley and flex coupling due to a cross-member limiting clearance for belt. New belt was difficult as it was much thicker than the old worn out one. It still went in without taking anything else off, by rotating the motor to help push the belt past the interference. If the flex coupling at the lower pulley was removed it would be easier to get the belt in, but I had very limited tools and was uncertain how it came apart.
7. New belt was very difficult to get over the fan and alternator pulley. Had to loosen the lower alternator bolt (13mm) significantly and removed the upper (12mm) completely so the alternator could be angled. There is also a small (10mm) bolt that had to be loosened on the alternator adjustment bracket also.
Greased everything (splines, bolts, etc.) before reassembly.
It's on and just need hook the mower deck back up. Even changed the oil and filter while under the tractor.
Also wanted to add the two drive belts that drive the mower pto were replaced. Kubota wanted over $130 for the two small belts. Thankfully Napa was able to cross-over the PN to 5L320W (5/8" wide by 32" long on the outside). Napa was about $30 for the pair.
The Kubota P/N's:
66021-25000 (Assy belt - pair of belts $134.42)
66021-25080 (Individual belt, $67.64 each)