The K code equalizer IS different to clear the left side exhaust manifold. The short arm to the clutch rod is as far to the block side as it will go.
It is not stronger then any other arm. It's the same soft steel construction.
An important factor to consider is that the original Ford part was designed only to work with the original clutch in the car. That clutch was never a serviced part and was only a production line part.
It was a 2,600 pound clutch. The service part from Ford at the time was a Ford Rebuilt unit and was rated at 2,800 pounds.
The service equalizer was not a heat treated part. It is soft untempered steel and the long arm doesn't have the strength to not twist under the load of anything greater then the original 2,600 pound clutch.
As far as I see and experience ALL aftermarket clutches are in the 3,200 pound range. They are going to twist up a "stock" equalizer like a piece of licorice candy.
You need to use a reinforced equalizer bar. That means it is either thicker on the long arm, seriously heat treated or both in order to not twist up.
You wouldn't see the failure immediately. What will happen is the long arm will bend a little at a time until it gets to the point that the clutch pedal can't travel far enough to release the clutch. That takes a little time. Maybe a few weeks, but it will fail unless you reinforce and temper the steel.
For me, one of the things I've learned over the years is how to make my own equalizer bars. This helps me since I have changed configurations in my 68 so many times between engine blocks, exhaust manifolds and headers that each time I needed a different configuration. I just started making my own and I suppose learned the techniques of the "village blacksmith" in how to temper soft steel into hardened steel.
It also taught me how to weld to survive.
Necessity is the Mother of invention in my case. It also came to be that form follows function and that isn't necessarily a pretty thing. Those are thick heavy welds and you can probably measure the weight of them on a bathroom scale.
A Concourse Judge would die of a conniption if they see it. I'm not sure if they are "innocent" individuals, but keep in mind that we should attempt to protect the innocent?
A quick way to recognize a "reinforced" equalizer is to look into the open end of the round tube.
The stock unit isn't very thick in the wall of the tube. Less then 1/8".
I found it necessary to go to a thicker wall and I use 3/16" wall DOM steel tube like on a motorcycle chassis.
The reason I mention this is that you may be buying from an unknowledgeable seller and when you ask them questions, they are just going to yes you. "Yes, yes, yes, this is the 'high-performance' equalizer", not knowing at all what they are talking about. Lots of them out there unfortunately.