You can replace the whole glass yerself cheap with a one piece.

Solid rear window glass is readliy available. If I break my slider like you, that's what I will do...I'll replace it with a one piece....and I will do it myself.

If you decide to keep the slider, order it from Toy or a glass place.....Either way, replace it yourself.

Remove the window like you would a one piece.

Then place the window on the floor and press down with one foot thru the open frame while you pull up on the alum frame in the middle of the top frame. Insert your slider half or halves into the slots then relax your strain. Then install the whole thing using WD-40 and cord.