1+ Seat squab  
2+ Squab cover  
3+ Tunnel panel  
4+ Tunnel panel cover  
5+ Seat cushion  
6+ Cushion cover  
7+ Setscrew  
8+ Clip  
9+ Plain washer  
10+ Shakeproof washer  
11+ Locknut  

The part numbers in the assembly image below relate to the product number in the table. Clicking on the part number will open up the relevant part details.