Vibration while in gear and stoped solved by replacing front driveshaft flex disc

[bmw540san]

As title states I had pretty significant vibration while in gear and sitting at the light for example. If I shifted to N or P the vibration would stop.
If you do search people mainly suggest motor mounts but I suspected someting else considering that vibration should be present the whole time if the motor mounts are bad.
Anyway, I did the careful insepction and found #1 to have hairline cracks:
https://www.realoem.com/bmw/enUS/sho...diagId=26_0175
When removed and compared to new part it apperas to have lost considerable amount of rigidity which it makes sense why it produced vibration.
During replacement I took the oportunity to inspect splines on the driveshaft and transfer case and found them have no wear whatsoever.
The flex disc was original at 129k miles and proximity to exhaust probably accelerated the wear.
So if you have these symptoms, it's worth checking it out.
When replacing make sure that arrows on flex disc point toward flanges and torque to 60NM.
You should replace the 6 bolts according to TIS but I didn't. They looked fine but I do understand they are exposed to stress. Having the lift in my garage I am under the car fairly often and I'll keep an eye on them.