Driving along, not turning steering wheel, accelerating, decelerating or braking....brief screeching sound from underneath followed by smell of burning: to hard shoulder. Recovery driver can find nothing visible amiss but guessing at diff/gearbox owing to oil on truck load bed. Starts & runs but 'groans' soon as in 2nd ( tentative trial in Travelodge car park) Anyone any idea as to likely cause? Having to decide if can afford a fix...if expensive - will have to be no. Hate the thought. Its a RRC with 300 tdi.