Ranco valve.

Your capillary tube goes and lies flat against the interior firewall until the end of the tube attaches to the blower assembly. It should have a small clamp at the end. This goes onto the bottom screw on the blower assembly where the tray attaches to the plenum, HOWEVER not all Rancos had this setup. Some had an abbreviated capillary tube that terminated almost at the valve itself. Whatever you do, DO NOT rupture the capillary line or rupture the bladder. If you do ,barring obtaining a replacement bladder, you have destroyed your Ranco.