Aftermarket kick down cables

There should be two holes in the bracket on the back of the engine. Put the largest drill bit in them to line up the hole in the pivoting bracket with the hole in the one bolted to the engine. Then adjust the middle linkage so the ball is even with the socket and just snaps in. Then take out the drill bit.

Next put your throttle on the carb as far back as it can go to wide open throttle (WOT). Then adjust the rod so that the rear of the slot is bottomed out to the back of the slot at WOT.

that is how to adjust the three piece kickdown linkage.

If your trans is built right, the kickdown should work fine. If not, I would have the trans checked by a good trans guy. Be sure that you take it to a good guy. I have only one guy that I trust and after he rebuilds a trans and I adjust the kickdown it shifts perfectly. Not to soon, not too late. You can leave the trans in "D" and stomp it from a good 30 mph roll and feel it kick down correctly.