Yes its possible. Read the post 2 above!
Linix it seems - unlike every other manufacturer use the same gearbox on every speed motor. 26 to 1. And instead they change the motor windings to adjust speed. I didnt know that and its a different way of doing the same thing. You still get less torque with higher speed etc. But it means that the motors armature will have different thickness wire, possibly different number slots, and more or less turns so your 30mOhm might be correct on your 8mph motors..
BM:
I have just had it on good authority (3 photos of the motor labels) by a member here for a different reason that instead of using different gearbox ratios the 5mph HD and the 6mph, 8mph motors all use the SAME gear ratio. And have different RPM ouput's. So they change the motors instead to alter max RPM. They may do this in a bunch of ways such as having different number of "slots". They look the same externally. So as in the hobby world, linix are doing it differently to all the previous manufacturers. So a 5 slot motor will be half as fast as a 10 or 11 slot one possible. And just as in the hobby world this is exactly the same thing as changing gearing. The faster motor has less torque. So net result is exactly the same as swapping gear ratios. I may also mean that they use thinner or fatter windings with a different number of turns on the armature. This will all mean that they may need different motor load compensation settings. that expressos claim that the stock settings for the 8mph motors was 30, instead of 45 may be correct.