Door Frame Clip for Malone Versa Rail Rack

I purchased a 58" Malone Versa Rail rack to transport my canoe on top of my 2018 Silverado. I went this route because I also have a cap on the truck and it’s the closest I can find to what my dad and brother use.

My dad and brother have racks built in the 80’s which use metal clips to secure them to the door frame of their trucks. The Malone has a strap that goes all the way through the cab.
I want to replace that strap with shorter ones and clips like they have but I can’t find any that work with my truck. The ones I found are not large enough.

Anyone know what that piece is called or have a place to get such things?