Just my 7 Yen (around 2 cents worth):
First of all you should (for yourself and as info for others when asking) determine WHICH Mitterteich, because there were two factories there: Rieber-Mitterteich and Porzellanfabrik Mitterteich. Both were - and are - confused not only by single people but also by folks that should know better (like replacements.com). Anyway, that would just need a glance at the marks - note however that Rieber also used marks just showing 'Mitterteich'. But as I said, no big deal and with a mark, one can roughly find out a period of production
That aside, you use the replacement.com's own pattern designation which in many many cases has nothing to do with the original name or number of a shape/decoration. For example assume the deco name is 'Kirschbluete' ... which you don't know and search like mad for MIT75, an inofficial designation. One is of course right to say that even if it's wrong, it's still something to hang on and all people seen so far used it, yada yada. My point is: don't take the MIT75 as Holy Grail, other people might just use something else. I bet one would not find the replacements.com number used in auctions in Europe, for example. And as eBay lately is the Holy House of Dimwits, many search results from the US don't show all European hits even if explicitly told to. Hence one misses tons of stuff ...
Hope that helps a bit