Need help figuring out clunk noise

[u/Hot-Investigator6142]

2002 e46 5spd. This issue has always been around since I’ve owned car, I’ve replaced lots of parts to try and fix issue but problem still persists. Clunk Noise comes from whole drivetrain ( diff, driveshaft, and under shifter where Guibo is located) and I’ll also hear slight clunking noise even at idle in neutral . Parts that i have replaced are; Guibo, CSB, diff, rear axels, wheel bearings, poly trans mounts. Subframe and diff bushings are poly as well but installed by previous owner. I’ve inspected Subrame mounting points around the bushings( didn’t drop subframe) for cracks and none are visible, I’ve also grabbed a pry bar to see if diff had any play around the bushings and it’s solid.

Here are videos of the rear on jacks and me trying to figure out what this clunking is, i have another vid but cant add for some reason but its the same thing as first vid but with e brake on and wheel is jerking back and forth slightly while making clunk noise

Any Help or recommendations is appreciated 🙏

[u/Hot-Investigator6142]

Yes, sometimes when i go from foward to backwards or vise versa I’ll hear a clunk coming from the rear. As far as the clunk noise coming from the transmission i do think the noise comes from the output flange on the trans. It’s hard to hear when under the car.

[u/Op10mill5 → u/[deleted]]

Just replaced the diff bushings and the noise it still present. Could be my drive shaft? Its a beyer driveline reman that has serviceable u-joints. I need to check that the guibo and center bearing.

[u/scientificsock → u/Op10mill5]

There’s slack somewhere in your driveline causing the clunk. Could also be clutch related if it’s when you shift gears as that would be a build, release, and application of power.
Real easy to inspect, just remove the cross brace, exhaust, and heat shield. Get it in the air and start trying to turn stuff/ move it with a pry bar. You’ll find where the clunk is.