When the W123 was introduced, the 280 and 300 models had the square lights, the round reflectors were standard on the lower spec models, 250 and down.

Around the "freshening" in 1980, all cars got the square lights.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles