Regardless of what ARB are saying the Secop/Danfos compressors should "Not" Clunk, Niether of mine do it and never have,
These compressors are Shock Mounted so this should not be happening,
Both my 47L and my 78L never do this and I have picked them up and shaken them and they still won't do it So what ever is causing the noise is because something has come loose or was never tightened up properly and this is a common fault with many brands of fridges especially domestic fridges, Snomaster do it at every bump in the road even on smooth blacktop. and its a PIA,
I have 4 fridges that use the the Secop/Danfos Compressors being the BD1.4F and the BD35F and the BD50F and not one of them make this sound, What ever you are being told is 100% "WRONG"
hope that helps.