Walk Behind Lawn Mowers

I have a Husqvarna 21" Rotary Lawn Mower purchased from Sears around 2006. Model# 917.374470. I am converting it from a rear-bagger to a side discharge. I lost the side Discharge Guard that came with the mower and I do not have the original owners manual. I went on line and downloaded an owners manual for the Model 917.374470 but the Mulcher Door Assembly and Discharge Guard shown are not the ones on my mower. The Mulcher Door assembly on my mower is attached to the mower housing by two short bolts which are part of the Door Assembly. The one shown in the manual is held on by one single bolt. When I oudered the Discharge on line I received one with one large slot for that single bolt which didn't fit my mower rather than one with two holes to match my mower housing. How can I order the correct Discharge Guard>