Hey all,

I’ve been recently troubleshooting a thud coming from my driveline/rear end, when I first purchased the car I double checked the vehicle for subframe cracks even though PO had recent inspection by dealership, couldn’t identify any via visual inspection so decided to tackle the differential bushings. I replaced all 3, job only slightly annoying, correct tools and watching youtube DIY videos are a must. Anyway put the car back together and still have the mysterious thud sound. It happens exclusively when disengaging the clutch when changing gear. Its not completely constant, usually more prevalent at lower RPMs.
I’ve done a bunch of reading on some of the culprits, and am going to check the subframe mounting points again tomorrow but if I still cant see any cracks would a thud sound be possible if no visible cracks (aware there could be small ones I cant see unless I drop rear end). Read about CSB and Guibo on the driveshaft but that seems to be more of vibration/whining issue no? When I was doing the bushing job examined the rear sway bar end links and bushings and seemed fine as well, but could these come into play? Any chance the differential could have some type of wear on its splines that would cause this sound?
Also will mention engine and transmission mounts have been replaced by me and I believe the clutch+flywheel(130k) are original.

Thanks ahead time and sorry for the word vomit just wanted to try add as much context as possible.