front flex in a rover will always be an issue.. been there got sick of tweeking things, bought a SG 3 link, problem solved:D,,,,,well for a rock toy NOT a tourer.
if you want it as a tourer what flex you have in the pic is shirt loads. if you want it as a rock toy then engineered mods are the only way.
as for the 3rds arms... your still replacing a rover radius arm with something thats almost identical in design.
i too would spend the money on a locker;)
cheers phil

