DOES THE HDK SUSPENSION K-MEMBER HANDLE BETTER THAN A T-BAR SUSPENSION?

I already have guessed with reasoning, but I see no similarity in the issues at hand, in that monte Carlo bars usually have lots of "real estate" to make a restricted connection, the lower suspension brace does not.
So enlighten me.
I have no idea what you are talking about in your guess or reasoning.

The similarity is easy to spot, rod ends are often used to have large and finite adjustments for placement of the ball end to a fixed position that might not always be in the exact same position, car to car....K to K. Welding causes distortion, sometimes it may only be a few thousands, but having that finite adjustment is the difference whether something slides in / on smoothly or has to be beat in / on.

No engineering studies or degrees required for the above evaluation....only need to work with it. Try it sometime.