Hello,
According to Joe Baughers impressive site at
http://www.joebaugher.com/usaf_fighters/p39_6.html 26 P-39D-3-BE and 11 P-39-D-4-BE were converted from earlier models for photo reconnaissance tasks. Helpfully the serial numbers of these machines are given.
However while using the search engine on the Aviation Archaeology site I came across a number of P-39D in service with recce units which were not amongst those listed by Joe Baugher. Examples include
41-6793- 30 TRS
41-28344-23 TRS
41-38281-124 RS
Is it simply the case that earlier unconverted P-39D-1-1BE served alongside the dedicated photo recce variants or were more machines converted to the P-39D-3-BE/P-39D-4-BE than stated.
Regards,
Clint