13" open and 9" closed with a one inch extension are expensive and only availble from a few suppliers if you use a shock that is 14" open and 9.5" closed you can used any make coilover type shock as its a std size
i have gaz units (without extension)and the bottom front lower wishbone shock bracket needs a small amount ground off
see this
http://www.haynes.co.uk/forums/showthread.php?t=5820