Is that a pipe bushing for the bolt to slide thru or a piece of something else?
I'm not sure, because I never saw one of these kits either, but according to the text in the service bulletin, I'm thinking it is 4 pieces of flat-stock set in place to straddle the bolts ....The width of the flat-stock will keep them from "tilting" and tightening the bolts should keep the reinforcements from sliding rearward.
The text says: "...insert two (2) into each frame tubing ...with front end flush with end of tubing."
I can't see the bottom illustration on the service bulletin clearly. .....Any help, Brian?