I go to the drive in quick lube place, where they have a "vacuum" that sucks a differential or trans dry and let them change it - you can look at what they get out to see how gritty it is .... OTOH, I've had 50 year old trucks that I'm sure have never been changed and they're still working
Bill
I bet the manual was written knowing the trucks would be used for hard service. Back then I think people bought trucks to do actual work. I suppose now in the later years the fluid would last a pretty long time. Good advice on sucking it out, that would make quick work of it!
Mike
