In brief, the OEM side racks come in two versions. One is side cases only, and they fit the OEM Suzuki cases, which are Kappa equivalents of the Givi V35s. This setup has two side bars, onto which the sidecase racks bolt with a joining bar across the outside of the rear mudguard. The OEM part numbers are:
990D0-17H00-065 (side case mount), and 990D0-17H00-060 (side mount bar)
The other setup is for the Suzuki top and side case set:
990D0-17H00-065 (side case mount), and 990D0-38G05-060 (top case mount). The difference is that the side bars continue round in a "U" shape which makes the base for the top box.
I personally don't like the Suzuki top case mount as it sits too close to the passenger, does away with the grab rail, and hasn't the mount for the Givi electrical connector to get brake and tail lights to the top box (in my one, a Givi V46).
I had the Givi PLX539 side racks, which are perfectly good, but they have a funny indicator bracket which relocates the indicators beside the rear number plate light, making them too close together and they wobble around. I never liked it.
I have the Givi FZ539 top case mount (monokey), and got myself the OEM Suzuki side case racks. They are 50mm wider than the Givi PLX539 racks and are mounted slightly differently. They bolt up just fine with the Givi FZ539 top case mount.
This is the full Givi setup (PLX539 and FZ539). Check the awful indicator mounting. The right side bolts to the exhaust mount and the left to a bolt that replaces the pin in the passenger footreats
The following pics show the FZ539 Givi top case mount with the OEM Suzuki racks. The lower mounts go behind the passenger footpeg mounts. You get all the bolts, spacers, and even the blanking plates for the rear indicators. (The indicator cables go underneath the tail light).
Much better positioned indicators:
The side racks will unbolt quite quickly from the side bars if needed.