**EDIT** There's a follow-up to this initial review after inflating the tires. Read on!
Well..... I installed the spool today. Unfortunately for me, a spool is not for me. I turned the machine around in the shop, in 2wd, and immediately noted that the steering was very heavy, particularly backing up, and if not moving- no way. That's on a cement floor, and I have power steering. I drove it out onto our very hard packed gravel yard- same deal- keep in mind, I run my Rip-Saw RT's very soft, and the rip-saws grip like pit-bulls on hard pack, pavement, rock, or ground they can sink their teeth into... So the spool isn't going to work for my riding style. We already know what a beast the machine will be driving all four wheels, so I don't think I need to go and run it through any mud holes or anything like that, cuz the most important thing to me was how it would react in tight trail situations with good traction. Now for the guys that love riding mud, the spool will be a very inexpensive alternative to the locker. I'm feeling a little concerned that the locker will have some of the same issues- particularly in 4wd, so I may have to 're-learn' my driving habits, as I almost always ride in 4wd...
As far as the install, it went very smoothly, the retaining pin for the cross pin came out without issue, and the spool itself fit really really good, with all the clearances really close. Something else I verified while I had the diff apart, the ring gear has 53 teeth, and the pinion 13 teeth for a calculated ratio of 4.08:1 (rounded up). I then verified that number by turning the driveshaft and counting the axle turns.
So, tomorrow I'm gonna tear it down again, and remove the spool.
Looking forward to trying the auto locker!....Next!