My upper arm modification looks exactly like the Ten T. I do not have the hinge pin or the upper rear pin retainer installed. I am using SNR towers. I used the stock Traxxas Slash camber link #3644. It comes as a kit with the large flange screws which I installed exactly like the Slash. To install the Slash camber link I had to grind the captured ball a little to fit into the C-Hub. Other balls could be used but the stock ball is to small for the traxxas rod end. The other end required that I drill the plastic bushing through so that the Traxxas large flange screw could push through for me to add a nylock nut to the other end. Works great so far. I will post any changes that may come from this modification.
I also installed STRC C-hubs at the same time. I don't notice any bump steer. The truck handled better and steering was more crisp. I hope to have pics sometime to share.
I was having issues with the stock upper arm turnbuckles. I replaced them with the 4mm Lunsford part which worked a while but in the end the plastic is too thin to hold well.