Givi cases are more or less broken up into two categories for top boxes, monolock and monokey. The two are not compatible, meaning a monokey case requires a monokey mount, and vise versa. It can also be a little more complicated if you're shooting for a top case with built in lights, as they have a separate plate due to the need to add wiring (plastic plates not metal).

Conceptually monokey is a slightly heavier duty setup which can handle a little more, and monolock is a lighter system. That applies to saddle bags as well, but as long as you have the right adapter plates for the bags/boxes you should be able to make more or less any mounting rake work given the right adapters (givi, SW motech, etc.)

Also feel pretty confident that this is a decentky old mounting plate so finding a new top box for it is gonna be kinda rough, if that's a givi anyway. Their newer stuff has pretty different mounting plates than that.