The parts for attaching the blade are shown on pages 5, 6, and 7.
Like I wrote before about the plow, you don't use the manual lift lever shown in the manual, if the Cub has Touch Control.
http://farmallcub.com/rudi_cub/www.clea ... index.html
IH made changes to the blade mounting parts in the 1st few years of the blades.
Earlier blades had no spring on the lift near the grille.
Below are pics from TM Tractor of the blade they say was made when a 1950 Cub was new. If the blade was bought with the tractor, it may have this style of blade.

http://www.tmtractor.com/tm-tractor/gim/blade54_001.htm