I think you're looking for a mezzanine board (that's the name of the interposer board you seem to be missing). Odd that they would strip them like that because they're really not useful for anything else.

I used to have a crapload of mezz boards around here but I don't know where they went. If I find any, you're welcome to a couple. I bought out Shreve Systems' old stock when they were liquidating intending to put more drives in my ANS, but I never got around to it. It just has an 18GB Fujitsu SCSI-2 in it now, which is enough for what it does.