I got my fillers from
infantimachine.com
This is the kit I bought, I have not yet installed them though.
http://infantimachine.com/~infanti/i...l-filler-panel
Much cheaper than Porterbuilt but the Porterbuilt pieces are much fancier. Also I dont think Infanti makes the corner piece. If you have the skill you could cut your own patches.
Here is the Porterbuilt kit
http://www.porterbuiltfabrication.co...ller-Panels-99
There are install pics in the Porterbuilt link. I like that they use one panel and it has a nice bead roll line in it. Swanky!
Pic 1 Infanti
Pic 2 Porterbuilt