There are 4 places that polaris put the vin numbers on magnums and sportsmans over the years.
1: Sticker on top of front plastics (usually gone within a couple of years)
2: Bottom of frame on forward left side (near the oil reservoir)
3: Under the seat
4: Downtube of the frame behind the right front wheel.
2006 Sportsman 450
27" Vampires on ITP Delta wheels
3 headlight mod
55w driving lights