Mine is 1:1, just curious since I've never seen one, does the 2:1 use L series belts? I had considered changing to the 2:1. The Y and Z could be swapped with parts available from McMaster, but how about the X, the driven one looks pressed or threaded onto the ball nut and the housing doesn't look big enough for a larger pulley.

What did you make these out of, 4140?