You should change the fluid and look for metal shavings in the pan. If there are any, it's probably rebuild time.

However, what is the condition of your flex disk? These only last about 60,000 miles in hard use, and cause hard shifts, especially downshifts. Bad diff mounts will also cause the diff to bounce pretty hard on shifts (thumps in the rear), and all can sound funny.

Replace the little rubber connector on the modulator line, it's probably leaking. In fact, inspect and replace if necessary ALL the vacuum lines, including the idle control valve hoses. Vac leaks will play merry hell with fuel mixture, and that will cause all sorts of vac variations, hence hard shifts sometimes and soft ones others.

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!