Well, mine is quite different indeed. I have the Deluxe 12" version, bought it at the end of march from Astro Optical in Melbourne who shipped it from their store in Sydney. (Bintel were sold out) . I think the cover was packed NOT in the mirror housing like the 1st release.
Anyway, I do believe the screw is still 5/16ths but only 5mm of the very end is threaded. The picture was taken on 5mm graph paper.
Oh, and great to hear the LB kit is coming along!