I bought this specific P/N (6643) after a quick research (I found a youtube Graph-Tech video recommending this specific piece to improve Jackson guitars).
When I installed the piece (procedure was easy even for me!! - there is a Graph Tech video on youtube explaining it for newcomers) I found that 1E and 2B strings did not fit properly to the hole when strings are tuned, and they are extremelly low (touching the frets).
Then, I made a wider research and I have found a reference of an original Jackson nut replacement: 0096769000: Its dimmensions are 43.0mm lenght x 6.5mm width x 8.9mm height, 35.1mm from 6E to 1E... Height was the problem.
More researches... an "old" Graph Tech card found on the internet revealed that model 6010 is the recomendation for a wide variety of Jackson models, including JS32: Height is correct, but width is also small (4.9mm: the nut hole of the guitar is made for something close to 6mm), and the shape is not as the original nut (quite "squared" with long and straigh holes for the strings, same appearence than this 6643)...
Models like 6143 (not easy to found) or 6060 seems to fit better (you have to reduce some dimmension but it is supposed to be easy).... Nevertheless the shape problem remains...
Finally I gave a new opportunity to the 6643 (with proper lenght, widht, distance between 1E and 6E and shape) adding a piece of "credit card" properly reshapped and glued to the bottom of the nut to increase height... Now it is working, but it gave me hours of work, and I am not sure whether the solution will be durable and if the sound is as good as it should be without the glued piece of card (probably not).
A recommendation: before to install a new nut, put the old one in front of the new, and compare the dimensions: ensure that lenght and width are similar (or slightly bigger in the new one,... remove materal is easy) and once pieces are in front, check the height of each string one by one. New nut shall be similar or slightly higher (then, remove material of the "floor" of the nut until heights are similar).
CONCLUSION: If you need a Graph Tech TUSQ nut on your Jackson guitar, make a better choice than the one I made.