Tools needed for 99 Mercury Rack & Pinion-specifically allen on steering knuckle on 1999 Mercury Cougar

My husband is replacing the rack & pinion on my daughter's 99 Mercury Cougar he has it almost apart, but has ran into an allen that he cannot figure out the size. He has standard & metric, but none seem to fit & of course due to location he can't see it very well, anyone know what type or size he is needing?? Any help would be appreciated, my daughter has MY car while he is fixing hers, which puts us down a vehicle!!

Asked by for the 1999 Mercury Cougar
May be a TORX (star) bit is what he needs, cant tell you what size though.