This latch with an extra escutchion type part

The 82-218 latch appears to be the exact replacement for my sliding glass door , which I have actually located in San Antonio Tx, BUT my latch has a extra escutchion type part that fits around the oval part of the latch and over the monting holes of the latch. These two parts are then assembled together with some kind of specialized rivet that has a 3/16 D, hole that then allows the whole assembly to be mounted to the door frame. This extra part is 4-9/16 x 7/8 x 1/2' Deep. There is an addtional part I see at your web site,Swisco# 89-021D( Die cast keeper) that is just like mine on the jamb side of the door, the extra part in question slips over the die cast keeper. So what I need is to be able to purchase the lach with the other part assmbled to it and ready to mount to the frame. Can you please help??