Although the upper mounting point is fixed, the wider front frame moves the chassis mounting point slightly forward.
Add to this the fact that 4/4, Plus4 and Roadster wire wheels have slightly different offset.
The 4/4 has least offset and so runs closer to the upper spring mounting. Given that the end of the reaction bar is well back on the chassis, with 185/70s on a 4/4 there may be clearance issues on the upper spring mount and rubbing on the sidewall.
Adjustment of the chassis mount point is limited!
