So ever since I bought my f150 about three months ago it makes a whining noise from the transmission while I am reversing it. What could be the cause of this? Should I bring it in for a trans flush and filter change? What would that run me?

 

Start simple
Have you checked the transfluid level?? this would apply to either automatic or standard transmission, not sure what you have but the odds are its a automatic.

If a automatic, & if it is shifting fine then a transmission drain and and replace the filter certainly couldn't hurt. I'd be a little weary of those flush machines, they do exchange the fluid better but some run some pretty high pressures doing it and that tends to create more problems down the road.

as for cost cant help you there, you're best bet is call around and ask in your local area