Sure!
Probably the picture you are thinking of was the one where the upper shock mount had torn after (bumpy) Lime Rock. You could see the added link in that photo. It's here:
https://img.photobucket.com/albums/v170/aeronca65t/Cars/sprite-shock.jpg
A better picture of the added triangulation link can be seen below.
The trailing arm itself is about 5/8" OD steel.
It is around 7.25" from center to center of the rod ends.
It would have been neater if I had a LH thread for one end but I didn't have a tap handy, so I need to take one end off to lengthen or shorten the arm. Not a big deal since it really hasn't changed any.
Be sure that the arm moves up and down without binding. It's better to disconnect the lever am and move it up and down without the king pin to be sure of this.
The lever end is attached to the arm by a piece of 1" by 3/16" steel that is roughly like an "S". This steel piece is held to the lever arm by the exisiting pinch bolt and the through-bolt. The plate on the other end is 2" by 3/16" and it is bent out at roughly a 30 degree angle. It's bolted to the car and also glued (with PL200 construction adhesive).
Remember that this can only be done on rubber bumper Midgets, but not earlier Spridgets (because the metal that the trailing arm attachs to does not exist on older cars.....it's part of the bumper reinforcement area). You might be able to add some material to an older car or add an arm behind the lever. Not sure.
The main benefit I have found is during heavy trailbraking from high speed. Before I added this, the car would move around under hard braking, sort of steering itself. I drive another Mk1 Sprite that runs large and very sticky bias Hoosiers and it's even worse. After this, the car is much more stable under hard braking during turn-in (my car has Carbotech pads and Brembo rotors but just stock calipers).
I need to improve my sway bar links with heim joints too....right now my setup is pretty agricultural.
Have fun!