Might be worth checking the toe setting again then if you're not sure.
As Pete says the 4-dr ARB gave about a degree more castor than the 3 door one - the increased self-centreing affect will help as well if you can get hold of one.

If you look at the original road tests the standard 3-doors were always noted for tramlining

This post might interest you https://passionford.com/forum/viewto...er=asc&start=0