Joreto found that the 350SDL exhaust manifold fits with the M103 if you drill new holes in the mounting flange. I would take a chance in a junkyard to see if the exhaust ports line up (mounting holes will not) with the M104 as they do in a M103. I just purchased a 300SDL turbo exhaust manifold from a forum member to slap on my M103. The manifold gasket listing is the same number for the 350SDL and 300SDL = same mounting = same size holes = (from my standpoint) same manifold. So you've got options if you want to go down this road...pretty much any diesel with an OM603 under the hood (late w126s, w124 300Ds, w140). You should be able to find one in a junkyard if you scour hard enough, might be able to use the turbo on them too if you wanted a spare. If you're planning on making a log-type custom maifold, you might as well give it a shot. Sure beats spending 1200 euros on a custom welded piece made for 500+ hp if you're not wanting to do that much.

IIRC the Mosselmann turbo kits are twin turbo and made to use t2/t25 turbos right? You would need a flange adapter to fit T3/T4s.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth