Unsolved Making a JBEAM prop spin

Hello,

I've added a chain-driven differential to my FSAE car and defined it in the prop section of the JBEAM file. It shows up in-game properly with the correct textures, but I'm not sure what to put in the func section. I'd like it to spin at the same rate as the rear wheels, but defining func as the name of a shaft in the powertrain section does not make it spin up. There shouldn't be any syntax errors as it responds and spins up with default funcs like brake and throttle.

Do I have to define this as an electrics item in a LUA file? I've included some code below:

"powertrain" : [
["type", "name", "inputName", "inputIndex"],
["torsionReactor", "torsionReactorR", "rearMotor", 1],
["shaft", "rear_chain", "torsionReactorR", 1],
["differential", "differential_R", "rear_chain", 1, {"diffType":"lsd", "gearRatio":"$finaldrive_R", "friction":8, "defaultVirtualInertia":0.25}],
],
"props": [
["func" , "mesh" , "idRef:", "idX:", "idY:" , "baseRotation" , "rotation" , "translation" , "min", "max", "offset", "multiplier"]
["rear_chain" ,"diff_gear", "a40","a41","a48", {"x":0, "y":180, "z":0}, {"x":1, "y":0, "z":0} , {"x":0.0, "y":0, "z":0}, -360, 360, 0, 1, {"baseTranslation":{"x":0.09,"y":0.165,"z":0.075}}],
],
"torsionReactorR": {
"torqueReactionNodes:":["a40","a41","a49"],
},

 

I tried renaming my powertrain and func to driveshaft_r, which is the same as the pickup and semi. Sadly it still doesn't move...

"powertrain" : [
["type", "name", "inputName", "inputIndex"],
["torsionReactor", "torsionReactorR", "rearMotor", 1],
["shaft", "driveshaft_r", "torsionReactorR", 1],
["differential", "differential_R", "driveshaft_r", 1, {"diffType":"lsd", "gearRatio":"$finaldrive_R", "friction":8, "defaultVirtualInertia":0.25}],
],
"props": [
["func" , "mesh" , "idRef:", "idX:", "idY:" , "baseRotation" , "rotation" , "translation" , "min", "max", "offset", "multiplier"]
["driveshaft_r" ,"diff_gear", "a40","a41","a48", {"x":0, "y":180, "z":0}, {"x":1, "y":0, "z":0} , {"x":0.0, "y":0, "z":0}, -360, 360, 0, 100, {"baseTranslation":{"x":0.09,"y":0.165,"z":0.075}}],
],

 

I renamed the rear_chain to driveshaft_r, again identical with the pickup and semi. The powertrain system is also working flawlessly, with the rearmotor sending torque to the torsionReactor, which sends it to the driveshaft_r, and then rear diff and half shafts. The powertrain UI app shows that the driveshaft has a real RPM value, but the prop still doesn't spin.