On my '50 Burb, the inside of the cab has a slot with a knotch at one end to keep it closed. Mine doesn't ratchet either, I'm guessing the friction of the lever and the wind will keep it open.

Buddy


"Keep the shiny side up....."
'50 GMC Suburban
'55 1st Chevy Pickup
http://community.webshots.com/user/buddyinak