Matthias, did you see the photo I´ve posted in adifferent thread? Do you have any additional information about the source of this pic?
http://forum.12oclockhigh.net/showthread.php?t=18913
Concerning the the engines I´m rather convinced the fuselages left Flossenbürg as complete units, i.e. with the DB 605s attached. All available photos prove this assumption. Without the engine, its bearers, the wiring and other necessary accessoires the firewall between engine compartment and cockpit looks rather "clean" and "empty" on all photos showing this assembly status. The Wertheim fuselages feature all those parts with loose wiring ends but without the engine. Even the canted struts supporting the engine bearer - which make only sense in the very moment when the DB gets fitted - are already attached.
http://www.koelzsch-restauration.de/.../Me-109_04.jpg
For unknown reasons the engines were removed somewhere between Flossenbürg and Wertheim IMHO.
Concerning the producers of the Daimler-Benz engines I have to pass this question to the experts. I only can say that just as the tail units the engine covers were built and painted at different locations. That´s why the camo areas and grey values don´t fit together on most Flossenbürg fuselages.
Regards
Fran