Does anyone know if/why 93 L27 exhaust manifolds wouldn't work on a 92 L67. After reading Mortehl'* post, I'm considering sending the EMs off my parts car to Hulkspeed. Visual inspection with L27'* in hand and L67'* on the car reveals only some heatshield differences.

Rear (right) exhaust manifold 92-95 Supercharged is all one interchangeable part (L67). Part number is 24500683.

L27 non-supercharged 92 is one part number. 25537100
And another part number for 93-94, identical to the L67 rear. 24500683

Did the 92 L27 have a seperate crossover pipe, or was the O2 sensor different?

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Front (left) exhast manifold:

92 L67 is unique with a 24501731 part number. Is the crossover part of this in 92? It is from 93-95. All one piece.

93-95 L67 is a 24502380, and this is shared with the 93/94 L27 as well.

92 L27 front (left) manifold lists two types. I'm assuming type one has no EGR outlet, and type two has one. Type 1 is 24501727 and type 2 is 24501743 (some 92'* did have the digital EGR, plastic upper intake, and Delco ICM/coils, but only in late production).

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So the big question to ask after all this is the very question you asked to begin with (I didn't do much but show the difference you mentioned):

Why is the front 92 L67 manifold different than the 93-95 L67 and 93/94 L27? I recall one wierd setup was a seperate crossover pipe, so that may be it. But I can't see that preventing you from switching over. However, it appears that it'* only the 92 L27 Type 1 that is seperate.

John, can you take a few pics of your front manifold?

O2 bung is the same. Crossovers are both part of the front mani. Again, the only differences I could see with mine still on my engine, were that the L27s had less shielding on the front.

I'll get some pics later of the L67s, but the L27s are at my parents'.

Maybe some good pics of Gravenge too? Both John'*? I'd like to print them and compare to my L67'*. Under the hood realtime. Bummer we didn't discuss this before our last two meetings in the NW. We had them all side by side.

Do L67 manifolds flow a lot better than the ones on the L27? Wouldn't they fit every year of 3800?

Look at the part numbers above. 93/94 L27 manifolds are the same part number as the 93-95 L67.

Oh then theres really no difference. But they should fit on the LN3

Don, I think you mean EGR bung?

Couldnt the O2 sensor be moved to the front?