IBM 5271 (PC3270) host interface options

Esteemed listmembers; I am restoring a ca. 1985 IBM 5271---the so-called 3270 PC. I received it intact, with a full complement of cards, cables, etc. It looks very much like it was shut down, removed from its original office installation, and then apparently left somewhere the squirrels could get to it (thus, "restoring"). I've vacuumed about forty pounds of sunflower seed hulls out of it. Blessedly, I haven't found any other signs of animal inhabitation. Anyway, my irrational fear of contracting hantavirus aside, I am wondering if somebody could tell me about what I suspect is the host interface adapter. All card slots are occupied: 1 - Async Adapter 2 - 5271 Graphics Adapter APA option 3 - 5271 Graphics Adapter 4 - 64-256KB Memory expansion card 5 - 5160 ST412 controller 6 - 5160 floppy controller 7 - the card I need help identifying 8 - 5271 Keyboard Adapter As there is no 3270 coax card and no open slot to have once held one, I suspect that the 3270 host interface is the unknown card in slot 7. I own IBM SDLC and Bisync adapter cards, and this one doesn't look like either. Physical characteristics: * 8-bit, short card. * One DB25F on the bulkhead. * 9x Oki M37S64-20; apparently 64Kx1 memories. * 34 pin .100" header, vertically, at back end of card (J2) * one 4-pos DIP switch at top right. * Pretty much everything else on the card is 74LS-series TTL or passive. It's built like IBM made it, but I can't find any obvious IBM-style part number on it, unless it's 2683541. Google is silent on this number. (update: I just noticed 6320999 in the etch, but that hasn't gotten me any closer to an answer). Anybody have any guesses? What other host attachment options were available for the 5271, besides 3270 coax? Thanks! ok bear