Here are two known Do 17 R photos (I am not certain about the first one as it could be some MV prototype, as there are some visible engine installation differences) - (K. Kössler article in Luftafahrt International), there is also one retouched factory photo in old Nowarra book on Do 17 -
According to Kössler and also documet from EADS archives (Flugleistungen Do 17 R) the engines were DB 601 A. Moreover rear upper gunner position was removed from this series.
regards,
Pawel