1964 Chrysler 300k torsion bars

Everywhere I've looked all mopars torsion bar adjustment bolts are located at the front on the car on the Lower control arm. However on my 300k the adjustment bolt is located to the rear of the torsion bar about below the front seats much like a Silverados suspension. Has anyone seen this before on an old mopar??

Btw I'm looking for some larger diameter bars and would like to know if any 41" mopar bars would work. Any help would be great!