If you are looking for the entire physical package (Disc + Case + Manual): XBOX Manual: Ssx 3 : Free Download, Borrow, and Streaming
If you prefer a pre-printed replacement, various retailers on eBay sell reproduction box art inserts specifically for original Xbox games. Complete Sets (CIB) SSX 3 [Xbox Classic]
You can often find sellers offering the SSX 3 Instruction Manual Only on eBay for around $4.99–$7.74 if you already own the disc and case. If you are looking for the entire physical
XBOX Manual: Ssx 3 : Free Download, Borrow, and Streaming : Internet Archive. Internet Archive SSX 3 [Xbox] : Electronic Arts: Video Games - Amazon.com SSX 3 [Xbox Classic]
You can find a high-quality scan of the original Xbox Manual for SSX 3 on the Internet Archive .