Printrbot LC V2 - Z Carraige design V1 Free 3D print model

I got tired of my Z Axis nut coming loose on my Printrbot so i sought to see if i could design a replacement for the assembly that was simpler, smaller, lighter, less screws and printable.

This is the first design, basically i took the Printrbot source files, reassembled them in 3dsMax to get an idea of where all the nuts, holes and rods went, then deleted it all and designed based around the placement of the nuts, rods and bearings. so far the print has come out great, but i need to print out the rod holder.

im not positive its is the Z carraige, since it holds the X carraige rods, so im not sure what this is called, does anyone know?