Hey guys, im looking to purchase an AM shift knob for my 08 mazda 3 gt (auto)

Looking at this one here, but not sure which thread size to go with. i know 10mmx1.25 is pretty good for mazdas but i also found online it said that 8mmx1.25 is the proper size for auto transmission. idk why there would be a difference between auto or manual in this case though since both are just a screw on knob?