Looking good so far, not much yo go on at the mo...
except you seem to have 4 too many rivets on top. Unless i'm just not seeing them in the ref picture you supplied.
Nice work 
www.stevenegan-cgi.com
"Your weapons are no match for ours! People of Mars, surrender!"
"Um, this isn't Mars. This is Earth."
"Earth? Earth-with-nuclear-weapons Earth?"
"Yes."
[long pause] "Friend!!"