ART - Are those your new 23-10.50 Firestones? They look good! You even got the tread facing the right way on them both!
BILL J. - Matt is correct, pulling the deck & mule drive only takes 5 minutes, and another 5 min to replace. But I find a simple bread pan sits inside the arms on the mule drive just right and holds the 1-1/2 quarts of oil from the Kohler. Have to be careful getting the pan out because it's full to within 1/2 to 1/4 inch of the top.
Far as swapping decks between mule drives on tractors, I would think that could cause problems. If you kept the mule drive with the same deck but on different tractors, not so much. I only have one deck for each tractor so can't swap things around.
The linkage and pivot points do wear over the years, and adjustments for height side-to-side and frt to back are needed. Depends on how hard you are on your deck BUSH-HOGGING weeds. The decks themselves can and will distort is treated rough, the 44 & 50 inch decks especially since they're made from lighter gauge steel.
I don't think you'll find ANY old CC decks with blade tip speeds approaching what today's zero-turn mowers have. I've never checked any of my decks but I thought someone years ago figured CC decks run around 15,000-16,000 feet per minute. Most zero-turn mowers are rated 18,000-19,000 FPM that I've seen. You can thank Purdue University for a lot of the issues with the mower decks. I read in one of my CC books that IH contracted out the sound reduction project to PU for the quiet-line tractors. And suprise surprise, the mower deck was one of the biggest contributors to noise while mowing so the slowed the deck speed down. Maybe that's why they had to offer the speed-up pulley. Even with the speed-up pulley the blades would only run 16,666 to 17,777 FPM, about 11.1% faster.
I should check my engine RPM with my tach someday, and then check mower spindle speed. I think my 38" deck has all three blades running at different speed. Should do the 982 while I'm at it.