The hitch tube of the Curt hitch part # C11405 that you referenced is totally open all the way through.
You may also be referring to the weld stop that some Class I hitches install in the tube to prevent the use of Class II accessories in them. Curt hitches do not have that.
Curt requires the use of their stabilizer strap part # 18050 when using their hitch to carry a non-supported load like a bike rack. I attached a review video for you to check for the strap as well. view full answer...
My contact at Titan advises that their Uni-Servo Hydraulic Right-Hand 10-inch brake assembly, part # T1878700, uses an aluminum servo. The left-hand side assembly is part # T1878800.
I have included a link to a product video for part # T1878700. view full answer...