I was having issues with mine in the '74 as well. Not auto click off and no horn. One of the members on the board pointed me here:
https://www.amazon.com/gp/product/B07S8GSKY...=UTF8&psc=1 and it works great so far.
Blinker and high beam switch works and the auto cancel works as expected. I have not finished setting up the horn yet because one of the PO's did a pretty good job of disconnecting everything.
And the best part is, it's very cost effective.