I'd go with Richard's figure, as a search of my own had several numbers, all just over the 700 odd off the top of my head.
Also, it agrees with this link, which has serial number details, thus making it the most likely to be right;
But here are the other links I looked up, some with different numbers, but worth a look anyway;
Fairchild Republic, took a bad hit when their follow on programme to the A-10, the T-46 jst trainer, was axed in the mid 80's.
T-46, an ungainly looking, twin turbofan, twin tail aircraft, was subject to cost escalation and production delays, perhaps also in the end not being a marketable basic trainer on the world market, with the arrival of high performance but much cheaper, turboprops such as the Tucano and Swiss PC
Fairchild with SAAB, developed the SF
.340 commuter aircraft, an attempt to be less reliant on the Pentagon, however it exited the programme well before the rewards of it's sales were realised, but now just to SAAB's benefit, for what reason, I don't know.