I did the driving test on both my Plaids, one 21” and the other 19”. They are about 275 vin apart.
21” Michelin
I notice the slight vibration at 40ish but not severe. To me it feel like the tire tread resonance. The groves are bigger and different on this vs the 19”. First picture is the Michelin 21” and second is the Pirelli 19”. I do notice under hard acceleration that there is some shutter. All test were done with low mode. I remember the shaft issue on my 2016 and 2020 Model X, but they were mainly with the suspension in high mode. I haven’t tried to set the suspension in high and flooring it. To me, when flooring it feel like slipping of the wheel and not shaft related. I can confirm by looking at all the tire dust after each time I play with the hard acceleration
19” Pirelli
I don’t have any vibration at 40ish. Tried to move higher to 50’s. Though I felt something, but so minor that not worth mentioning. Again under hard acceleration from 30 up, I do feel the studdering, but I still attribute that feeling to losing grip on the road. The traction control as I understand it is working like crazy varying the power to the limits to prevent slip. With the plaid there is a little bit of slip. I also notice the under hard acceleration vibration is worse on the 19” which makes more sense since we lose 1cm front and rear on the contact patch. Hard acceleration from 60 doesn’t produce any of these vibrations. So I don’t think it is shaft related.
hope this helps. I don’t think what I’m feeling is shaft related. I know what the shaft issues are and how they feel in the MX since I’ve had them on both. They make more of a mechanical noise. These studdering at lower speed high acceleration to me feels like lost of grip and the system trying to keep at the limits. None of this can be felt at higher pedal smashing at all on both cars.
Both cars are on 2021.12.4.9. Both are the quietest cars I've had from Tesla and I've had all of them starting with the 2013 MS, 2016 MX, 2018 M3, 2020 MX, 2020 MY. I hope you find and fix the issue that is troubling you.