Not exactly, but close enough you can use the W123 seats in a W115. The rear seat cushion is different -- the front seats may be almost identical except for height -- I think you need a spacer under them as the W115 seats are a little taller.

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!