these are all good suggestions... motor mounts, tranny mount, tailshaft bushing, rear suspension bushings, dont forget the 'torque rod' bushings. Obviously part of the rear suspension bushing replacement...Mine were shot and this allowed the rear end to rotate about the axle very slightly. I replaced these bushings and things got quieter, then I overhauled the driveline with new output shaft bushing, u-joints, center bearing & carrier, and that really made things smooth. There is a procedure for shimming the center driveline carrier.. I think Volvo actually published a TSB regarding this. A center bearing that is not properly shimmed will cause a shudder / vibration under load. I think Don Foster had posted a procedure but if my memory serves me..I believe it involved shimming up the bearing 1/2" w/ wahshers then test drive, then lower the stack by one washer until the vibration is gone. Now that the search function is working, you should be able to find it in the archives,

Matt

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'82 DL - 150k, '93 940 - 93k