I had to look rather deeply at this oddities kept coming up.
The GF's are Canada only, The US does not sell them so support is very limited.
The GF just has different mounts on the arms than the other models.
They use a one bolt mount, not 2 bolt mount.
That shoe just uses 2 bolts.
It's not an adjustability thing.
Are you trying to adapt this to the GF arms with only one hole on the arms?
Contact a Canadian Kubota dealer and see what mount they are using now.
If it's a mount with 2 bolt holes, then the arms on the GF have changed.
You can either alter your arms to fit the new 2 bolt pattern or you can alster the shoe to fit a single bolt pattern.