Grant does not supply enough parts in any of their kits to make the horn work in a Mopar, nor enough parts to make the turn signals "Auto Cancel"
The Copper ring/hub that bridges the connection between the column and wheel is missing from all of their kits, as well as the circle clip/ring with the tang protruding from it to cancel the turn signal cam.
I encountered this when I installed a Grant wheel on my '73 Duster in March. At first I thought I got an installation kit that had been packaged wrong (possibly missing pieces), got a replacement kit, same exact parts. (that don't quite match the instructions included), then I looked online and sure enough, even that parts list and instructions don't include or mention the required parts.
I have a horn button under the edge of the dash on the '73 because of that, and manually cancel the turn signals after turning.