Good. If it adheres (necessarily) to the realities of Apple's architecture, it has a IIci PDS connector that will plug into the cache slot of a IIci (only) without an adapter. IIsi and SE/30 use the same IIsi '030 PDS' (to IIci PDS or 'cache' slot) adapter. There are specialized 030 PDS adapters for LC, IIcx, &c., &c. In short, it is the adapter that makes it 'fit', by translating from a given Mac's PDS to a IIci's PDS.
Had you asked a week ago, the 50MHz chips would nave been immediately available at considerably less than the price above.
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