also "Vienna Arsenl" and "Nibelungenwerk " seem 2 different entities according to this quote
Severely damaged tanks from the Russian front were initially shipped back to Germany, or to the Nibelungenwerk or the Vienna Arsenal for repair;[23][24][25] but the prospect of inevitable delays often meant that vehicles were instead cannibalised at the front for parts
https://thereaderwiki.com/en/List_of_WWII_Maybach_engines
so to sum up IMO producer should be Vienna Arsenal to all unless it has a machine gun on the commanders cuppola which makes a Series 4 late war vehicle, preferably call it Stumpanzer 43 and Brummbär Sd Kfz 166 as extra info
