The back window is not hard but the side windows can be hard with
new seals.
The glass and seal pushes out by hand.
New seal goes on glass and rope goes in the mid. grove of the seal to
lip over the metal.
You need a 6' rope no bigger than 1/4"
silicone spray or good soapy water to make seal slick
a hook tool to help seal go over the metal (AutoZone)
a friend to hold the glass in pleace and push in at the same time
Simple if you know what you are doing.
You can ask a glassman to do it on side for a few $.