Six weeks is rather a long time for the short end of the estimate.
It appears that, rather then adding a rotor ground, the later versions removed the Aegis ground brush ring instead. Rotor bearings went to non-conductive "ceramic" balls and nylon cages. The reluctor chamber got a 5mm vent hole to the rotor cavity. Triple-lip seal went to single lip. Probably another dozen or two things.
2014 Rav4 EV, Shoreline Blue Pearl, #2609, first use 04Jun2014, 49k miles (Aug2017), OpenEV-SE 40A. First DU replacement May2018 59k.
2018 Model 3 LR AWD, blue. 9.6kw solar