The US Navy operated a pair of modernised OV-10Gs - borrowed from NASA - for a lengthy light attack evaluation (Combat Dragon II) which included a significant operational deployment. At one time Boeing stood ready to relaunch production of an OV-10X, subject to a minimum 100 aircraft order, but with the tie in with Paramount on the Mwari and the attack pretensions of their T-X contender I suspect they've decided against it. Certainly they did not offer to demonstrate the OV-10Gs in the soon to start OA-X fly off!