how to replace the driveshaft flex joint on 2002 BMW 530i

when taking off and making the axle turn u can hear a knock noise 4rm 10-20mps then it goes away until u slow down to a stop were the knock noise returns. the noise it located in the center of the car between tha transmission and driveshaft

Asked by for the 2002 BMW 530i
replacing a flex joint requires having an above-ground
lift, as you must remove the complete exhaust system to access and drop the driveshaft. is is unsafe to attempt this job "on the ground."