Not sure the size, but you have to be careful.
They are tighter tolerance threads. If you chase them with a normal die then you will make them looser. Actually, you need to be careful with most fasteners on the A chassis because many are tighter tolerance. I hand clean all the threads with wire wheels and picks.
Do not try to chase threads on the nut, it is extremely hard. It will break a tap.
I strongly suggest that you use only original hardware here.