Different length hinge pin braces would be used depending on the caster block inserts you are using to lengthen/shorten the upper arm (and also change the upper arm angle.) In my experience, I would typically use the front brace to stiffen the front of the car and lose a little bit of steering compared to running without the brace.
Max and Dave will probably chime in with more hands-on experience and info, though.
Chris Hillier | 5280 Raceway | www.5280raceway.com | Racing. Elevated.
Destiny | LRP America | Protoform | Xenon/JFT | Gravity RC | Motiv | Sanwa | Max.FX