Need a little mod rewrite help


Okay here is the dealio.... The forum has been around for about 18 years total and I have moved from several software packages to Xenforo where I am now. I have a way to rectify my attachment issues long term but need to be able to get a mod rewrite working for a particular issue.

I have embedded in some image tags the following URL structure:


My forum is located here now:


Here is my current .htaccess file and I also have the VB rewrites scripts running too!

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} ^ [nc]
RewriteRule ^(.*)$$1 [R=301,L]
RewriteRule ^[^/]+/([0-9]+)-[^\./]+\.html$ /forum/threads/$1/ [R=301,L]
RewriteBase /forum
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^.*$ - [NC,L]
RewriteRule ^(data/|js/|styles/|install/|favicon\.ico|crossdomain\.xml|r obots\.txt) - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

I need to get the links on the first line working so that I can import and attach the images to the xenforo standard data structure. I can do the second part manually, I just need a rewrite that allows me to type the old url in and have it work. I need the script to see the old URL with iB_html request and redirect it to where the images are currently located...