Sorted, Rob has sent the size details of the 888 pump and they are different to the 851, probably due to the different mounting. Rob said his pump is made by Walbro, with a total pump length of 70mm + 25mm reduced diameter of 36mm for mounting in the rubber boot. The 851 body is 100mm long by 50mm diameter. So looks like I'll be selling a pump to someone who needs the spares for an 851. Cheers guys.