While I'm waiting on a new transmission for my XT2 SLX50 Fab, I just replaced the fast attach spindles and blades with a kit that has a 6 point center hole from 8tenparts.com I was tired of pulling the deck off, flipping it upside down, and beating the collars with a mallet to get the blades off. While I can't mow yet, here's my take so far. My Cub spindle sheaves are 5" dia., and the 8ten are the same diameter. The height is exactly the same. The bolt hole pattern is exact. You'll need a 10mm to remove the Cub spindles, and a 1/2" to install the 8ten. I matched up the new blades with my high lift blades, and are the same length. A big difference is the 8ten blades are thicker and have a 1" longer cutting edge at each end than the OME Cub blades. The only downside is that they don't supply the 5/8"-18 nuts for the blades. I emailed them (got a response within 2 hours on Sunday) asking if the spindles were pre-greased (they are) and suggested they add a few bucks to the price and supply the nuts. Customer service was passing the suggestion on to their product folks, so that may no be an issue sometime in the future. The website was easy to use. Pick equipment type, make, and model. The price isn't much more than a set of the S pattern blades.
Here's what I ordered for MY 50" deck.
https://8tenparts.com/products/8ten-mk1002313