I couldn't find it last night, but I remembered the Radius Magic Bus card turning their proprietary interconnect perpendicular to the SE PDS and shifting it to the slot at the back of the case. It was the expansion slot bracket that held it in place. It came with the FPD card and I never needed it because it takes the place of the Radius16/25 in an unaccelerated SE.

My bad, haven't played with that setup since the deal for a Radius FPD went bad over ten years ago. Got a crazy shipping & handling quote from a seller within easy driving distance. He wouldn't allow a local pickup, lesson learned, I'm glad eBay closed that shipping fee loophole.