Bill, I didn’t build out the frame at all beyond using the supplied LL extensions. I installed a very narrow strip of 1/16” foam on each side of the shell. Works like a Kato to release the chassis. And I cut a couple of thin strips of cardstock and glued to the top of chassis for vertical height as I felt it was a mm too low as is. What I did do was install a “dashboard” and rear deck lid also made from card (cut down Kato packaging in my case since green) for light control on the body since my LEDs are chassis mounted. Glad to take a picture tonight if it will be helpful?