I also have this newer inner transom plate. There is a washer that fits down in the rubber coating. I don’t have the part number anymore but it takes the place of the spring washer. The rubber coating replaces the fiber washer. Good luck with the search

I think he's referring to the lower nut that the long bolt threads into ? the only thing that goes in the horse shoe shape area is the nut

Hey all,
thanks for the advice/info, i think you're right ph1971...this rubber replaces the fibre washer.
I'll have look into this.
Thanks all