following the off topic tangent...
There was a Sonnet made card called a QuadDoubler, which was confirmed to have worked with the 3640 accellerator on the Amiga (from memory). The Quaddoubler was originally made for the quadra or centris macs. There were a few versions, I believe. At least some had L2 cache. I don't know if the L2 cached version worked with miggies or not. I believe all quaddoublers have pmmu, heat sink, and a faster clock. The card is a piggy-back style socket, which sits in the original '040 socket, and has it's own 040 socket for it's resident chip.
this page is a miggy site, with a dead link to an article about the sonnet quaddoubler. There is an extraction from that article
here, maybe half way down the page. The article doesn't mention L2 cache at all, so maybe it was the non cached adapter which was used successfully with the Amiga.
Anyone else have any info on L2 caches?
edit- some erroneous claims
