Renarts, there is something strange going on here. I have the Military Vehicles in Detail, SdKfz 250/1 to 250/12, by Terry Gander. There "appeared" to be another book, SdKfz 250-251, with a different cover, but it doesn't cover the 251 at all! Check out this link; http://www.historyofmilitary.com/Military_Vehicles_in_Detail_Sdkfz2501To25012_Miltary_Vehicles_in_Detail_1_0711029423.html
RedButcher, I have a few inside photos of a restored 251/1 ausf D. I also have Osprey's and Schiffer's books on the 251, as well as some others. I'll take a look to see what I have and post back in a bit.