Does it still have the tank mount rubbers on the frame? I think on the 91 and 92 they are screwed on, whereas they are glued on with the 89 and 90 frames. The top shock mount is bolted on with the 89, so that is another thing you could look for. I think the subframe on the 91 and 92 models is different, but I'm not 100% sure and whether it's easy to pick in photos. Hopefully some else can confirm this.