Remove your existing shock. Measure it's height... from center of top bolt to center of the bottom bolt. Also measure the width of the spring area. Also measure the size of the bolts (top and bottom). And lastly measure the width of the perch... area (top and bottom) where the bolt goes through.
With these measurements... you can start to track down shocks that will fit your application. Such as an example shock here off fleabay.
http://www.ebay.com/itm/10-5-Pit-Bik...RWePWP&vxp=mtr
Hope that helps. Cheers!