truck pulls to the right

my girl friend just bought a 1999 explorerxlt 4.0 . they replaced all 4 ball joints and upper bushings and they said they couldnt do an alignment on the truck. Now the truck pulls to the right and some times when you give it gas it seems to pull both ways. someone looked at the truck for her and said it was the torsion bars and bushings. can the torsion bars cause this or is it something else. I was a mechanic for 15 years its been a long time for me i looked at the truck but i didnt see anything wrong with the torsion bars. toe in on the front passanger tire is out stabilizer bar and bushings seem fine the onei thing i can see was maybe the lower control arm bushings.