The Extrusion Axis field is gone in 0.9.5. From the release notes, it was apparently added in 0.5.4 but for the life of me I cannot find it in 0.9.5.
I have to globally replace all extruder gcode references from E's to A's after slicing in order to run Slic3r code on my Cupcake.
Uhm, do all Makerbot flavors need A instead of E?
Should we set A automatically when the makerbot G-code flavor is selected?
Linked to #853, waiting for feedback
According to this page makerbot project which points out that extruder 1 and two uses prefix A and B. Also on this page [makerbot Driver](https://github.com/makerbot/s3g/blob/master/makerbot_driver/MachineDetector.py(http://github.com) you can see that only the Replicator 1 and 2 support the A and B prefix.
So base on this quick search it looks like the Thing-o-matic and the replicators use a sligly different version of gcode.
Makerbot/makerware G-code flavor was updated in the meanwhile.