List looks good to me...here is some info on some of the non-kitted versions, which hopefully can be used to make scratchbuilding or kitbashing much easier.
251/11 - this cablelayer version has a cable reel mounted on the right front fender, and the crew members carry special hooked poles for laying the cable from inside the halftrack. Two more cable reels replace the right two benches inside the halftrack.
You can obtain both the reels and the poles from the Dragon Kettenkrad cable layer kit.
251/12 - had the FuG-8 frame antenna. Carried the "scherenfernrohr", the tripod-mounted scissors binoculars, and the red-and-white striped "winkelmessgeraet", or range measuring tool. As far as I can tell there was no actual modification, only the addition of rangefinding equipment. Crew of six - driver, gunner and four artillery spotters.
251/13 - sound recording vehicle. All I could find was the names of the recording equipment - so if you can find pictures, you can probably make up the rest.
Sachgebiet 27-4, Geraet 4012 = Satz Schallaufnahmegeraete (set of burst recording equipment)
Sachgebiet 27-4, Geraet 4398 = Satz Auswertegeraete für Schallmessbatterie (set of deduction equipment for burst measuring battery)
Sachgebiet 27-88, Geraet 8829 = Satz Einbauteile für KW(3T) Schallaufnahme (set of construction-parts for burst recording equipment)
Sachgebiet 27-88, Geraet 8835 = Satz Einbauteile für KW(2T) Schallmesstrupp (set of construction-parts for burst measuring company)
251/14 - same equipment as above but I believe this vehicle looked quite different. This is my own conclusion, so I'm not sure it's accurate, but since the railcar loading specs of the 251/14 specify its height at 3 feet higher than any other 251, I'm guessing that this unidentified photo is of a 251/14:
The FuG-8 frame antenna was always removed and dissasembled for railway transport, so that ca't be what is creating the height difference. Looks like a rather involved scratchbuild, if anyone out there is feeling ambitious...
251/15 - flash detecting and measuring vehicle. Once again I only have the names of the equipment used.
Sachgebiet 27-4, Geraet 4399 = Satz Auswertegeraete für Lichtmessbatterie (set of deduction equipment for light measuring battery)
Sachgebiet 27-88, Geraet 8828 = Satz Einbauteile für KW(3T) Lichtauswertebatterie (set of construction-parts for light deduction battery)
251/18 - something of a replacement for the 251/6. Equipment is as follows:
FuG-5 radio with 2 m rod antenna
FuG-12 radio with 2 m rod antenna
Scherenfernrohr (Scissors telescope)
Map Table
251/19 - telephone vehicle. Operated with the 251/11, carried a switchboard unit and standard German field telephones.
Also, there are a few other wild variants if you (dupes) want to include any of them:
Sd.Kfz 251 fuer 7.5cm PaK42 L/70 auf 3t Zgkw - Fitted with 7.5cm PaK44 L/70.
Sd.Kfz 251 fuer 7.5cm Kwk 43 L/71 - Fitted with 7.5cm Kwk 43 L/71.
Sd.Kfz 251 mit 10.5cm Feldhaubitze - fitted with 105mm Howitzer.
Sd.Kfz 251 mit PanzerJagerKanone 90mm - similar to the version mounting the 88, but better armor.
Sd.Kfz 251 mit sPzB41 Gerlach 28/20 Panzerbusche field improvisation. (can swipe the mount from the dragon 250/11 kit.)
Sd.Kfz 251 mit 88mm KwK 43 - 1943 factory modification, not very successful as only one was built.
Sd.Kfz 251 mit Vielfach Rak WrT34 (vs) - Fitted with US 60 tube T34 'Calliope' rocket launcher.
I also found this picture of a Stuka zu Fuss firing, and thought it was too cool not to share