Have you looked at the Redirection plugin? You could make a rewrite rule for something like this: /([^\/]+/([1-9]+)/([^/]+)/? and then have it redirect to http://newsite.com/$1/$3, or something along those lines at least. I think you could do this with .htaccess as well, but I’m not familiar enough with the format for it to give you code in good conscious.
