Would seem I have an unconfirmed answer - my brothers mechanic says 12mm but the thread count unkown. Stopped into the Nissan dealer last night and he show me one off an old Quest - looks like the thread is 1.25. Not sure how this thread #ing works but the more coarse thread is a 1.75 as I found those at homedepot last night and there is also a 1.50 thread as per the bolt/nut sizing display.

M12 - 1.25

I my quest for the Quest bolts continues - I have 2 possible sources - a local trailer dealer and or Brafasco(larger nuts and bolt dealer).

I will post my findings later for those that may need in the future.