Overlord extruder

I'm upgrading OVP to dual head version. For this I need second extruder.

Hardware required:
4x M3x10mm screws
4x M3x20mm screws
4x M3 nuts
1x Spring - http://www.ebay.com/itm/141279958021
1x MK8 extruder gear - http://www.ebay.com/itm/371193389087
1x U-groove ball bearing 3*10*3mm - http://www.ebay.com/itm/331596903845
2x tube connector, 4mm - http://www.ebay.com/itm/141794766973
1x NEMA17 stepper motor (fits original overlord motor)

Assembly should be straight forward.
Any sugges