from memory here is the generational changes.
24/7--double action only.
24/7 pro- double action/ single action
24/7 Pro D/S- double action--single action --with a de-cocker.
there were litterly hundreds of thousands made I would bet!
BUT-- over the years many have bit the dust and also this was a recall item and so most that survived were returned to Taurus and replaced with G2 I think it was.
you might want to review the recall notice and decide if you wish to keep /use/ have this weapon.
hope this helps and is correct a far as I can say!