I'm not sure you will be able to find Munich DME. I've only seen it as LME. I'd suggest you use some Pilsner DME and mash the Munich instead.
If you do have a source for Munich DME, please let us know. I'd love to get my hands on some.
Yeah, I was working on faith. I don't recall seeing Munich DME either come to think of it, but I have seen Munich LME too. I'll bump my OG up occasionally with pale DME by a few points, or make a small hop experimentation batch with Briess DME, but that covers it nowadays.