You can source the brackets from a lot of places.
For example
Custom billet shock clamps for Fox and King 2.5" X 2.5" shock reservoirs and bodies.These shock clamps are proudly made in the USA from a solid piece of 6061-T6 aircraft grade aluminum. They are 3/4" (wide) thick and milled on each side to ensure a perfect fit. These clamps will work for...
store.custombuiltmotors.com
Do you know if they came with misaligment spacers ? My Kings have them cause the shocks must be spaced a little away from the upper mount for a ply and play install.
You can also ask
@revitupmoto33 where he got his, He's got Kings 2.5 though but his rears were not RAM specific and looked like yours initially, These were his Kings originally if i remember he said they were setup for Ford Truck so he had the source the needed misalignment spacers and id guess the res brackets as well. There is everything you can think of for these shocks so it shoudn't be hard to find a solution that can work for you.
You should be able to find them locally in Canada hopefully so you won't have to wait too long.
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You can see his Icons had a similar bracket and held in place with what it looks steel hose clamps. just a different style bracket that's all. in this case the Icons are 2.0 so the bracket diameter will be smaller. make sure you get them for 2.5 body shocks.
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Good luck.