You will need to replace the front subframe bushings (a nice rainy saturday job, not really terribly diffucult but time consuming). It will drive MUCH better afterwards.

Your vibration is very likely drive train related, but I would guess tires in spite of them being new, simply because you report different vibration on different road surfaces. Note that stiff front suspension parts can do goofy things, as can a bad steering damper (replace that, too).

You defintely need to check the kingpins -- jack the front wheels off the ground and see how hard it is to turn the front wheels by hand at the tire. If it's not smooth and easy, knock the tie rods off and see which side is stiff. Check the tie rods while you are at it, likely you need tie rods, drag link, and damper.

Find all 14 grease fittings and give them a good three or four squirts of synthetic grease. Repeat at least every 3000 miles or three months. This may cure the stiff steering. Could also be the box, in which case the wheels will pivot easily with the tie rods off.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!