[Using Cura 2.5 with Flashforge Creator / Makerbot Replicator 1 dual / or clone]

This is the gcode I've pieced together from various sources & got working. I have to set up each extruder as a separate printer. So I can use the left or the right but no dual extrusion. With the X3GWriter plugin by Ghostkeeper cura will output x3g.

Right Extruder Start Gcode

; begin

M136 ; tell the firmware we're starting a build

M73 P0 ; reset build progress

G130 X118 Y118 A118 B118 ; set vref's to default

M190 S{print_bed_temperature} ; set bed temp, don't wait

M104 S{print_temperature} T0 ; set right nozzle temp, don't waitdisable right nozzle, don't wait

M104 S0 T1 ; disable left nozzle, don't wait

T0 ; home on the right extruder

G90 ; set positioning to absolute

G28 X Y Z ; home XYZ at default home feedrates

G92 X0 Y0 Z0 A0 B0 ; define this as Z=0, the other coords are technically unnecessary but x3g requires them so gpx will make some up

G1 Z5 ; move the platform 5mm down

G28 Z F500 ; so we can home z again slowly

M132 X Y Z ; Recall stored home offsets

G1 X-95 Y-73 Z30 F7000; move to waiting position (front left corner of print bed)

M116 ; wait for target temperatures to be reached. GPX only, RepG doesn't understand

G92 E0 ; set current extruder position as 0 so that E15 below makes sense

G1 Z{first_layer_height} F6000.000; move to first layer height

G1 X100 Y-73 F7000.000; move to front right corner of bed

G1 X-90 Y-73 E24 F2000.000; extrude a line of filament across the front edge of the bed

G4 P2000; wait for ooze to slow

G1 Z0 F6000.000; lower nozzle height to 0

G1 X-95; wipe nozzle

G1 Z{first_layer_height} F6000.000; set nozzle to first layer height

G1 F7000; ensure fast travel to first print move

G92 E0 ; set E to 0 again because the slicer's next extrusion is relative to this 0

;end

Left Extruder Start Gcode

; begin

M136 ; tell the firmware we're starting a build

M73 P0 ; reset build progress

G130 X118 Y118 A118 B118 ; set vref's to default

M190 S{print_bed_temperature} ; set bed temp, don't wait

M104 S0 T0 ; disable right nozzle, don't wait

M104 S{print_temperature} T1 ; set left nozzle temp, don't wait

T1 ; home on the left extruder

G90 ; set positioning to absolute

G28 X Y Z ; home XYZ at default home feedrates

G92 X0 Y0 Z0 A0 B0 ; define this as Z=0, the other coords are technically unnecessary but x3g requires them so gpx will make some up

G1 Z5 ; move the platform 5mm down

G28 Z F500 ; so we can home z again slowly

M132 X Y Z ; Recall stored home offsets

G1 X-95 Y-73 Z30 F7000; move to waiting position (front left corner of print bed)

T1 ; select left extruder

M116 ; wait for target temperatures to be reached. GPX only, RepG doesn't understand

G92 E0 ; set current extruder position as 0 so that E15 below makes sense

G1 Z{first_layer_height} F6000.000; move to first layer height

G1 X100 Y-73 F7000.000; move to front right corner of bed

G1 X-90 Y-73 E24 F2000.000; extrude a line of filament across the front edge of the bed

G4 P2000; wait for ooze to slow

G1 Z0 F6000.000; lower nozzle height to 0

G1 X-95; wipe nozzle

G1 Z{first_layer_height} F6000.000; set nozzle to first layer height

G1 F7000; ensure fast travel to first print move

G92 E0 ; set E to 0 again because the slicer's next extrusion is relative to this 0

;end

I use the same end gcode for both extruders

M73 P100 ; end build progress

M140 S0 ; set bed temperature to 0

M104 S0 T0 ; set extruder temperature to 0

M104 S0 T1 ; set extruder temperature to 0

G92 E1

G1 E-5 F300

G28 X Y F2500 ; home X and Y axes

M18 ; disable all stepper motors

M70 P5 (We <3 Making Things!)

M72 P1 ; Play Ta-Da song

Hope this helps some of you.