Hey guys,
The Texan II and the Harvard II are both the same airframe made in North America by Raytheon (same company that produces the King Air line of products) under contract by Pilatus (Switzerland). The Texan II and Harvard II are derivatives of the Pilatus PC9 MkII. If you were to go to the Pilatus web site (which I will include below) there is a quick overview of tech data available. Also, any aircraft manufacturer will, within limits, modify the aircraft to meet the needs of the customer. So it is not to hard to believe that Pilatus/Raytheon would manufacture the same airframe but will have different options/mods for each individual customer.
Keep in mind that the "PC9" family of aircraft are in service not only in North America as the Texan/Harvard II but the Saudi's, Auzzie's and Slovenian just to name a few also use them as a training platform also.
I have also seen a picture of the PC9 with a variety of weapons for it to be fitted with. I will try to find it.
Here is the link!
http://www.pilatus-aircraft.com/html/en/products/index_32.asp?NavL1ID=31&NavL2ID=0&NavL3ID=0&NavL4ID=0&NavL5ID=0&NavL6ID=0&L=1
Cheers!
Still Looking