I just replaced the upper control arms on my 08 Scab as both ball joints were absolutely shot. Can anyone explain to me though, why my repair manual says to get an alignment done after replacing them?

I know on the older f150s there was a torsion key on the control arms that you adjusted to correct your alignment or sometimes level your ride (with aftermarket torsion keys), but the new trucks simply have a pivot bolt on both sides and a ball joint.

So why the need for an alignment?