Well, there are still some mysteries left to solve regarding engines made by "Wilhelm Gröning, Lüdenscheid" and/or "Heinrich Gröning, Lüdenscheid" (which sometimes appear as "Henrich und Gröning, Lüdenscheid") the forerunners of WILESCO in Lüdenscheid,
BUT
"Lüdenscheid" is a small industrial town in the "Märkischer Kreis" in the north-western corner of the famous Sauerland region in North-Rhine-Westphalia. For all of you who have never heard of this part of the world before (99%, I guess), no, it is not close to Hobbit-Land, but about 45km straight south (with a touch of east) of Dortmund (soccer, black/yellow, ykwim??),
so definitely it is and has always been a part of West-Germany (or "good" Germany, in Cold War terms).
Thus,
these are not GDR/DDR/East German engines!
I have to admit, however, that I was tempted to see them as East-German products when I first encountered them all those years ago...