For the most part they are compatible, but there are some exceptions. If you have an old KZ900/1000 or GS1100/1150 slider basket equipped with the steel inner backing plate, it is not possible to use that with a Gen II multistage. The Gen II uses a plate which is pinned to the inside of the basket, it is not possible to install that into one of these old baskets. The GSXR 1000 does not use a pinned plate due to the factory design of the clutch and isn't restricted, any MTC GSXR 1000 slider basket can be used with a Gen II.
Later model KZ and GS slider baskets have eliminated the need for the inner plate and are solid aluminum, which can be drilled for the pin holes if not already equipped. The newer bikes didn't have these plates and are not subject to this restriction.
If you are not sure if you basket has the holes, look inside the bottom for 3 blind holes drilled next to the rivet heads. If those are present, the slider basket is ready to use with a Gen II. Don't worry if the holes are not in there, we can put those holes in your later model MTC slider basket, just send it in with your order.