Hi Twosmoker86, welcome to the site. The water cooled 500 engines fall in four categories: 85, 86-87, 88, and 89 and up. The 85 is the first water cooled, and does not have the KIPS. The 86-87 are similar to the 88 on the top, but very different on the bottom. The 88 is a one year wonder that is similar to the 86-87 on top, but more like the 89 and up on the bottom. There were a few changes to the motor after 89, but those parts are interchangeable with the earlier models. While I have not tried to swap a water pump seal, I would think that the amount of difference between the 86-87 and 88 and up bottom ends would make that seal different. Rocky Mountain ATVMC shows that they currently have ten OEM Kawasaki 86 water pump seals in stock. I would recommend using the OEM parts where still available. It's also a good idea to replace the bearings as well, as long as you have the clutch cover off anyway. Post some pics of your bike if you get a chance. We love to see what everyone is riding!