http://cgi.ebay.com/ebaymotors/OHLIN...38157079QQrdZ1 Or you can use a DU440 but the hose is only 440mm so you need to get a longer hose. Get them from the US for about US$700. Shock lenght is 330mm. As far as I'm aware all 851/888's except the tricolors (I'm not sure on them) have the same dimentions for suspension.
And why do you guys go on about the "SP rocker" my what was standard 1990 851 Biposto has one.
Griff