Unknown Steel Tandem bike large /medium Sugino AT custom

Up for auction is a very nice vintage tandem mountain bike frameset with cranks and brakes. I found this tandem on OfferUp. The seller was a scrapper who does home clean outs and the area he said this came from is known as a high end area. I picked it up because I thought it was interesting. I added some wheels I had here at the time (not included) and tried to mock it together but it’s too big for me. I hoped I would get taller and be able to fit it but that never happened.
Frame and fork are put together very nicely there tons of Fillit brazing throughout. I don’t know much else about this frameset so please look at the photos to see what all is included. If you have any questions or need more photos please contact me. I will ship but it’s going to be pretty expensive due to the size of the frame. I also DO NOT currently have a box for this yet so it may take longer than 5 days to ship. Frame has a lot of similarities to Co-Motion, Salsa, Santana, Trek, Burly, Cannondale