Sorry... I was out all day... That Shock - I'd suggest removing one of the ones that is working, and match that one to a new one. Why? Well, a shock compresses to a certain minimum length (when the suspension bottoms out) and you want a new one that compresses at least that "short." And, it also extends to a certain maximum length (when suspension tops out) and you want a shock that extends at least that "long." By removing a good shock, you can also tell if it's gas-charged. With the Long and Short of the shock, whether gas or not, and the diameter of the piston chamber (the small end), you should be well on the way to a decent match.