I know this is an ancient thread. But the 2002 Sportsman 400 that I have, always dripped oil. On further exam I noticed someone had tried to epoxy it previously. I took the old plastic tank off. I looked at my '02 500 HO and realized I could use a tank off that model that is aluminum, it bolts in original mounts. Main difference is that the 500 uses the banjo fitting where the bolt goes right through the fitting. The 400 uses the barb type hoses. I used the original fitting with the oil screen off the 400. That required re-tapping the tank bottom oil fitting to 1/2 inch pipe thread. The return line to 3/8. Also it required modifying the oil inlet as it is recessed under the tank on the 500 and can't twist the elbow fitting on. The tank cost me $15 bucks including freight on e-bay. It is a little more difficult to check the oil now. But, it's the same way as it is on the 500.. Also the aluminum tank is finned and will help cool the oil.. Perhaps this can help someone down the line.