At the old Fornebu Airport, it seems BU registered its -200s to the US.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/130275500@N02">G B_NZ</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/130275500@N02/15946696667/">Braathens B737-200 N7031F at FBU</a>