1900D:
Present MTOW is 17120, MRW 17230. These were upped about 3-4 years ago with a paperwork change. Why? People are getting fatter, I suppose. They airplane had the structural margin to do it already built in, the just validated preformance numbers for the new weight.
Present MZFW is 15700 as of maybe 10 months ago, also with a paperwork change. After the Air Midwest accident in CLT standard passenger weights going from 170 to near 200 in much of the United States. There was a very wide gap between the old MZFW of 15165 and the new MTOW of 17120, compounded by the std. weight increase,. Our airline was faced with winter weights of 208 (!) per passenger, which meant you could take maybe 17 people, 17 bags, and you'd already reached your MZFW. Our passenger weights have been rationalized since then, baggage weights have increased, and CG limits have been narrowed, which means that we are now CG critical before being limited by MTOW on most flights. At least I could figure a max weight payload with my calculator - c. of g. is difficult to plot without a whizwheel! It's always something.
D-model is certified to Part 23, Amendment 34 standards.
I'm afraid I can't help with any C-model questions. But I do have one: How do you not give yourself a lobotomy every time you go up the stairs in the beloved UCs?