This is the base for RichRaps Quick-Fit X carriage for a Printrbot LC, so that one doesn't have to replace the whole carriage assembly.
1) print this part
2) print plate 1 (the "flat" thing) of RichRaps version
3) print the latch from the original Quick-Fit X carraige
4) put it all together and enjoy
side note I: the one I printed didn't have the hole for that one screw of the carriage mount, so the one on the model is untested (however, well measured). If anyone prints this model, I'd love to know if it fits as expected.
side note II: I didn't have the correct screws handy, hence the toothpicks.