[Seaplanes]

Thanks to the log book of test pilot Heinrich of the Heinkel factory in Rostock-Marienehe and the repair and maintenance reports from Bundesarhiv-Militärarchiv plus some other sources, the following production break-down can be made for the He 51:
W.Nr. 25-132 He 51C Factory not known.First aircraft delivered in February 1936.
W.Nr. 242-249 He 51C Factory not known
W.Nr. 429-430 He 51a + He 51b two prototypes by Heinkel
W.Nr. 801-890 He 51C Factory not known
W.Nr. 994-995 He 51V-5 and V-6 by Heinkel
W.Nr. 996-1009 He 51D (See) by Heinkel
W.Nr. 1010-1123 He 51C by Heinkel
W.Nr. 1435-1492 He 51C by Heinkel
W.Nr. 1493-1509 He 51D (See) by Heinkel
W.Nr. 1541-1570 He 51C Factory not known
W.Nr. 1767-1780 He 51C Factory not known
W.Nr. 2134-2158 He 51C Factory not known
W.Nr. 2192-2193 He 51C or D possibly Arado
W.Nr. 2201-2203 He 51C or D possibly Arado
This indicates a production of about 500 aircraft.
Apart from the Heinkel production, I have no links to the other factories involved in the He 51 production, Arado, Erla, AGO and Fieseler.
Is there anyone out there who has the missing links. Please give references to source.