My late grandfathers memoirs have been online at Feldgrau for ages: http://www.feldgrau.com/articles.php?ID=30
Here are some corrections and amendments:
In October 35 we were designated III Bataillon/Infanterie-Regiment 69, and our first batallion commander was Oberstleutnant Spengler. After this, we had years of practice.
That is correct, he was at first in IR 69, but after October 1937 he was in 6./IR 90 (mot.)
In the beginning of November 42 (something) happened that changed my destiny: An order from Heeres-Personalamt, Berlin, said that all former policemen were to join a Feldgendarmerie-Ersatz-Abteilung. I was finally to get an officer education, being a Hauptfeldwebel by now. I was happy to get away from the frontline, the school was in Lodz, Poland. I stayed in Lodz for two months, and got orders to lead a transport of 65 Feld-Gendarmen to Kaukasus. The train was set up in Warsaw.
The FG-Ersatz-Abteilung was Feldgendarmerie Ersatz-Abteilung X. After that, he was deployed to Feldgendarmerie-Abteilung 682 (mot.).
On 5.10.43 we were deployed to an Infanterie-Regiment, but this was destroyed before we could join. Ended up in 231.Infanterie-Division, (the) commanding general was Block. At first, we were the reserve unit.
It was not 231 ID, but 294 ID. His unit was 2./Gren.Rgt 514. After recovering from his wounds, he was ordered to Gren.Ers.Btl 31, but it is not likely that he joined that unit as the war was close to ending.