Greetings everyone, this is my first post here, but in searching for an answer I was pointed this way by some pilot friends.

I am working on some aviation prints of various commercial and military aircraft and currently have been working on some prints of 737-700 series aircraft. One of them will be of VR-59's C-40A Clippers (based at NAS Fort Worth JRB/Carswell Field). In my research on the various external details of the 737-700 for my artwork, I've come across what looks like two different air data probe systems (I think that's the right terminology....), one of the civilian 737-700s and one which appears unique to the C-40As.

Here are some links to Airliners.net pics to illustrate:

http://www.airliners.net/open.file/0599788/L/
http://www.airliners.net/open.file/0623403/L/

The above two shots are of a 737-600, but I think it should be the same across the NG family.

http://www.airliners.net/open.file/1038025/L/

The above single link is to the left side of a C-40A Clipper.

Differences I noted:

1. The Clipper has two pitot probes on the left side whereas the other has only one and its placed further forward.

2. There is a small hatch under the cockpit window on the right side of the civilian NGs but on the Clipper that small hatch/panel is on both sides under the cockpit.

3. I believe it's the AoA vane that is under the pitot probe on the left side of the civilian NG but on the Clipper it is between the two pitot probes.

I try and make my illustrations as accurate as possible and a lot of times I have to ask questions that don't necessarily affect what I end up doing, but I like to at least understand the differences for future projects I have planned.

So my question is this:

Do C-40A Clippers have a different air data system than civilian NGs and if so, is it due to some sort of increased redundancy that the Navy requires?

Thanks to everyone in advance!