Seat plans that differ between travel sites

As a newbie to this site and as you wil see form my few previous posts - I am cross checking seat plans before making the Fairphils first UC booking.
We will be flying on the LHR-EWR route thus 747 config 4.
My problem is tha the seat configurations given on Seatguru, Seat Expert, and Expert Flyer do not check!
Both Seatguru and Seat Expert show 13 rows of UC seats on the main deck.
Whereas an enquiry on Expertflyer shows 16 rows of seat.
Has anyone an idea why
Also I cannot find seat plans onthe VS site - is there one?
Many thanks

Hi

VS site seat plans...

http://www.virgin-atlantic.com/en/gb/al ... /index.jsp

Hope this helps
Marc

Originally posted by Fairphil

We will be flying on the LHR-EWR route thus 747 config 4.

This isn't 100% guaranteed. If you take a look in the which aircraft section on this website you'll see that the route has also been serviced in the past 3 months(admittedly much less frequently)by the 340-600.
DL