YKK No 5 Zipper, can buy them on eBay.
I have found that the material that you have to feed the zip onto can be very floppy and therefore hard to get the zip on. Get someone to grab the material with some needle nosed pliers and pull it tight, then a couple of drops of tin superglue onto the material. This sets in seconds and makes the material rigid making it much easier to slide the zipper on.
Make sure your zip goes easily around the window section, mine caught on the window itself in a couple of sections, just needed slight trimming.