In general an axle is a centre shaft for a rotating wheel or gear. So In general axle shaft is on which the hub of the wheel is mounted. In a rear wheel drive, on side on the axle is attached to the differential assembly and the other side is attached to the hub.
The average cost of a vinyl replacement window is between $400-$575 per window for a double hung. That price includes the cost of the new vinyl replacement window and the installation of it. The big difference in price would be for reasons like the manufacturer of the vinyl window (which series you go with in their line), grids, low-e and argon gas for example. Vinyl casement pocket replacement window:
Typical costs: Expect to pay an average of $300-$700 per window for replacements placed inside existing (and structurally intact) window frames, but it could go as high as $1,000 per window, for a range of $3,000-$10,000 for a one-story, three-bedroom home with 10 windows.