Originally Posted by whipplem104

Well, I have been a Mercedes technician both in and out of the dealerships for 17 years. In fact I was just doing a m104 head today. I have never replaced the seals between the upper and lower manifolds or seen anyone else replace them that I have worked with. Does not mean they are not getting old but still not something that I would say is problematic.
I think that 700ish is pretty good. Having a flange cut is fairly expensive in small quantities. I asked to have the one I made duplicated by a machine shop and was quoted in the 250-300 each for quantities of 10.
This is not a engine that you are going to make 1000 manifolds or more and sell them.
But if you got the skills then get to work.
You can machine the grooves for the rubber seals or use the earlier gasket that was used on the m120 engines as well.
You do have to consider that you will have to deal with the throttle linkage and transmission cable when moving the throttle body.