The SP2 swingarm will fit into an SP1 frame, but they are not directly interchangeable.
The SP2 swingarm pivot bolt is smaller in diameter, so an insert is fit into rear of the engine where the bolt passes through.
Plus, the pivot bolt, related adjust bolts, and hardware will need to be obtained to mount the swingarm.
Not that difficult, but not as simple as some think.
Thanks everyone for all the help. So with that said i have a 05 and I'm in need of a swingarm anybody got one for sale. I have a chromed 01 if anyone is interested in some type of swap i can provide pics. Thanks again