Mickey - Not sure if this may help, but below is a picture of the 1957 Chevy Accessory Installation Manual instruction page for the truck sun visor. Should be same process for your ‘56.

No idea if the piece you have has enough flex in it to install starting at the center per the instructions or not.

Maybe you could protect the mounting surfaces with painters tape and attempt a test fit, with some helping hands of course.

Not a one person job IMHO.
Attachments
IMG_6998.jpeg (279.51 KB, 142 downloads)


~ Dan
1951 Chevy 3 window 3100
Follow this story in the DITY Gallery
"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)