If I remember correctly the Walker exhaust catalog of 40 years ago listed the same headpipes for both 383 and 440 dual exhaust applications. Obviously there is a difference in the position of the manifold flange between the two.

Somebody check my math but if the 440 deck is .750 taller that would place the headpipe flange about a half inch higher and a half inch closer to the fenderwells than on the 383 – assuming identical HP manifolds for both engines.

Given that difference I assume the OEM headpipes were different between the two engines? I know some 440’s had H-pipes which would make them different but I’m just asking about standard dual exhaust