Squealing Triton

Hello All

My 98 Triton has developed I guess what`s best described as a mid pitched squeal.It starts at around 50km/h and keeps going from there.It remains constant and doesn`t change regardless of speed.You can get off the accelerator and put it into neutral and the noise is still there until the vehicle drops below 50km/h.I have rotated the tyres front to back and that hasn`t made any difference.I can`t pick whether it`s coming from the front or the back.Underneath there is some movement in the tailshaft centre bearing and the left front wheel has slight top to bottom movement ...everything else appears to be ok..Soooo apart from selling it and getting a Cruiser lol any ideas

Terry