it is normal for perdanas to face gearbox problem. be it SEi or v6. it's something u cant avoid. some may advise to rebuild gearbox, while some may advise to source a japanese (from halfcut) unit.
gearbox failure is inevitable. it's just a matter of how u solve it. many people sold their perdanas because they cannot tahan replacing gearboxes every now and then. perdanas are good cars, with good overall package. gearbox reliability is its only weakness.