I guess the first thing to figure out is which chassis you have. Personally, every SE that I've seen had an chassis that appeared to be identical to the SE/30. But I have also heard that some SE chassis did not have a hole to accomodate the vertical PDS cards found in the SE/30. (I've only seen one SE PDS card, and it was parallel to the SE mainboard IIRC.)

Does that mesh with what you know?