David thanks for your inquiry; in answer to your question:
On page one of this thread you will find a photo of a scratch built transfer case as created by Opaperinik. There is also a link there to several MAZ-537 photo walk-arounds provided thanks to Adam Berhidi.
Also the original Russian Tech Manual & Parts Manual for the 537 are available as free downloads if you search this Armorama site and/or the internet. there are some very nice perspective drawings of both the Transfer Case and the Transmission.
In addition, my scratch built transfer case and transmission for the 537 are shown on pages 2 & 3 of this thread.
Finally on page 2 you will find a link to the company "E63 Modelli de Carta". This firm offers a FREE download of a WORD file that allows you to print out flat 1/35th scale paper templates of the entire truck so you can build your own version of any MAZ part using these templates.

That about does it. I hope this gives you a path to the research you need.
Happy Modeling and Happy Holidays!