Lm8uu quick release carriage for Prusa Mendel

So I wanted a quick change X carriage that allows me to leave alone the bushings and rods, as much as possible.

Also, I am printing PLA, and there are just too many reports of melted/warped/softened X carriages floating around to be at ease with a PLA carriage. However, this should not be a problem with the bushing holders because of the heatsinking effect of metal.

I like GregFrost's three bushings X-carriage http://www.thingiverse.com/thing:9869 , but I think the side with two bushings s