Theres no difference in the tanks fitment.
If a SP1 tank is used on a 2003, you might notice that the graphics don't line up perfectly with the 2003 wing on the side fairing. But it's close.
The graphics should match ok for 2000, 2001, 2002, and 2004 bikes.
There was issues with the SP1 gas tanks leaking on the underside where the rear bracket is welded to the tank. You'd want to inspect that for any signs of leakage. It usually turns the paint a very dark red if it leaks.
A picture of the underside where the hinge is and where the fuel pump mounts would be very helpful. Also a pic of the inside of the tank would be nice.