I don't think it's a '3.5"' shock, just so people know what you're looking for.
I think it might be a 165mm (eye to eye) with 38mm stroke (which in application gives you 3.5" wheel travel).
Think, because I believe it's the same as the Trance shock I have, but it might even be the shorter version Fox do... best measure it and post the eye-to-eye if not the stroke length.