Hi

The exhaust studs are M10 X 1.5.
Older 240Ds have M8 X 1.25 studs to hold the chain tensioner, but your 83 uses bolts there.
The front most exhaust stud has a over all length of 42mm, the next 4 are 65 mm long.

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76 240 D. Bought in 1998 for $25.
85 300D. Got it for free with a bad engine. ( Sold )
60 Unimog 404. What was left of it, was given to me. Now powerd by 617A.
88 560 SEL. Bought without engine and trans. Now powerd by 617A.
67 250 SE. Cuope. For resto or sale.
64 220SE. For resto.