ARB's
 

Is it possible to fit a ARB out of line? I.e slightly to far left or right?

Its the only thing left I can think of thats making the car wander to the left.

has it only just started doing it?

have you had the geo/alignment fully checked?

Did you have geo done when you put steves old shocks on.

I only replaced a back one, I had a full Geo done a while ago, was way out, had it adjusted, but its allways wandered to the left slightly.

I may have had the Geo done before I fitted the ARBs actually...

ARB's cant really have any effect on geometry.............

Agreed.
I would guess it's prob brake slight bind, worn bush, track rod end worn, etc etc
Best bet Nick is to get it on 4 wheel laser set up, that will pint point the prob.

Or sell me the arbs! PMSL