w 140 question

[Sylvester]

hi.. guys i have 93 mercedes 300 se w140 and my problem is, im gitting a poping/clunking sound from the rear how do i tell if its the flex disk are the cv joints. i look under the car and the disk look ok. but maby not though, the noise gets louder when i accelerate but i still can here it while cruising please help me thank you.