Testors had one in 1/48. It was basic. Needs a lot of work to make it passable. There are resin and PE sets for it though.
Hasegawa has one in 1/72. Needs a little added work, also. They also released a version like the one in the top picture, an OV-10D, with a new nose piece cast in white metal.
There is another in 1/72, Academy I think, but I believe it is the Hasegawa kit reboxed.
Those are the only ones that I know of.
Good luck. You may still be able to find them.
Randie