Ok, thanks. Looks like the track is just held in with a few screws on each side and bottom. Is it as simple as unscrew the old screw in the new? Track is mounted to the tiles so if the new holes are in different spots I guess I would have to drill through the tiles? I'm reasonably handy but have not done this before.

What have you been thinking of doing with your glass/track @pauls234?

I'm thinking I will have to replace it entirely, track and all, but was hoping someone who's done this before would chime in to tell me that its an easy job, unscrew the old, screw in the new, done!

As long as you get a similar style frame you should be ok. The only screws which go into the tile are in the side rails; there should be no screws going into the curb (or bathtub). The screws you might be seeing by the bottom rail are probably the ones for the divider piece, but those go into the bottom rail not the shower curb. You will have lots of caulk or silicone to clean off, but even if the holes are in different places the side rails should cover them.

remove the doors, lift off the top rail, unscrew the side rails and carefully pry up the bottom rail. Clean surfaces thoroughly and follow directions to install your new shower doors. If you need to drill new holes into tile, remember to break the surface of the tile with an awl before you drill. You might need to cut top and bottom rails to fit, but a hacksaw will work fine. Silicone lots of places.

Thanks blubird, it was drilling new holes into tiles that I was most concerned about so appreciate the tip on using an awl.

I can get replacement glass, but no one addresses how to reuse the top rali that th old glass was in. How do you remove the broken glass in that rail so you can use on the new glass, Ive tried prying it out if groove with small screw driver , however it doesnt seem to come out easiely. does this tell me the rail CANT BE REUSED on the new glass?