NEW Quality ADL Lower Ball Joint for Mazda MX-5, Eunos Roadster - Mk1, Mk2 and Mk2.5 - all models 1989 to 2005, including all mounting bolts, nuts and split pin.
There is no need to worry about the thread size, they are different on Mk1 and Mk2. This is all you need to fit the lower joint.
Typically an MOT failure. It's easier to fit one of these, than buying a rubber!