If you look closely at this photo you'll see that where the "shock and coil spring" should be - there is only a square piece of tubing -- he's using this to set his ride height --- to build around - and this will also tell him his length of shock -- and coil --
The coil will have to be ordered based on the weight of the car etc -- but if you have a "known" car - then you can find the weight of the car via the interent - or the manufacturers website etc (of the coils etc - not the factory that built the car...)
http://www.clubcobra.com/photopost/d...788_Small_.JPG