This is an early fork of my generic head mount (http://www.thingiverse.com/thing:159390) that is specifically suited to the J-head mount of the E3D (3mm filament).
The vertical size is slightly smaller than that of the stock head, slightly bigger on the left X: so DO CHECK your end stops before you run this head else homing will make some noise you do not want to hear ;)
Still no attached fan for the deposited material. I enclosed the heater block with loose kapton to isolate it, and I use a 120mm powerful fan to blow on the platform instead. It makes the whole head lighter, and more importantly, it reduces the wobble at the nozzle.
Printed itself in Nylon ;)
0.18mm layers, 100% infill
Using M3 screws only. I forgot to record the sizes so I let you check (and report to me so I can complete the description) ;)
Once the top and bottom parts are attached to each other, you can mount the whole just by removing the two horizontal screws that clamp the bearings. There is onnly one way to do so, and it is quite faste once you get it.
FInally, the fan has a notch on a side, meant to leave room for the Y bearing (did not print this one on my setup, but it probably would help).