there is a slight humming noise in the front when driving the car. We are heading on a trip which is 500 miles round trip. the garage said front differentials with transfer case and rear differentials are needed. Is car safe to take on trip?
when do rear/front differentials absolutely need to be replaced? on 2006 Chevrolet Equinox
Theoretically, they never "absolutely" need to be replaced unless they are physically broken. And, unless the vehicle is 4 wheel drive or All-Wheel drive, there will not be a front differential or transfer case. As far as the humming noise, have it diagnosed by a good shop. It could be tire or front hub bearing noise. If the vehicle does have a front differential and transfer case, it could be gear or bearing noise from one of those as well. Take it to someone who knows what they are doing.