Isaac asked for opinions on this 3Rensho (ebay item no. 320225441769).
Some crucial details are not visible in the photos. For example, I imagine that all of the "aerodynamics" models were late enough to have "superends," the socketed attachment for the rear dropouts. I can't tell from the photos whether this frame has them (note: this isn't much more than speculation on my part, but I do have a circa-1984 3Rensho brochure that doesn't show either the aerodynamics model or superends). Also, my "aerodynamics" model has a top-of-the-downtube shifter boss, which isn't visible (to me, anyway) in any of the auction photos. Without these distinguishing details I would doubt the frame is the model claimed.
The lugs are very similar to mine, except that the headtube ring portion of the head lugs (on the auction frame) have an interesting taper, decreasing in height at the front of the headtube. Mine is more conventional. The fastback seatstay attachment on the ebay frame looks about right, but perhaps a little crude.
My frame (a 56cm c-t-c) has three cable guides on the top tube. This one appears to have two. It is a little hard to tell whether the full-frame photo is for the same frame as the detailed photos. Does it look to anyone else as if someone has tried to file off the serial number on the bottom? The serial numbers on my two 3Renshos are very distinct and deep, easily visible through the paint.
Even with these differences, the ebay frame has the "feel" of a 3Rensho to me. But I'm easily misled by my own vivid imagination at times!
Portola Valley, CA USA