The ESP Guitar Company

hey guys, the locking nut on my trusty m-ii finally needs a replacement. seems to be 43mm but floyd don't make one that size. and yet i've seen other standard series with 42mm and e-ii with 42mm. lots and lots of conflicting information regarding this topic, even more confusing as a lefty haha. would this gotoh one be a suitable replacement?  eBay link

or is the r3 or r4 (lefty version) the correct one?

any help would be much appreciated before i take it to a shop

thanks 

jacob