What is the differens in the hardware in the drive train in P85D, 85D and 70D. I have read about all kind of different things about this. From that all drive units are the same with differens software and different gearing in the front and the back to that all models have different drive units. I think for my self that there are two different drive units A and B and also different software to all models. P85D has A and B 85D has A and A 70D has A and A 85 has B Does someone know for sure how it is?