Did whoever responded from Look say that they don't believe this frame is a Look at all (based on the serial number) or just that it doesn't look like a KG131?

I'm not a Look marque expert, so I don't know what kind of variation there was in the frame numbering. All the Look frames I've seen so far had a number on the underside of the bb shell. I would like to find out if they ever put serial numbers on the inside of the NDS dropout like on the mystery frame.

Also, have you determined that this frame is actually all aluminum or is it carbon?



Appearance-wise, I think the model that most closely matches what you have there is the Carbolook 660 (from ~1993-95 era). It's interesting that if you look them up online, you'll almost find more resprayed frames than the ones still with original decals.

Here are some pics:









Here are details from the 1995 catalog (of the 4 bikes in the series, only the Carbolook 660 had external cable routing; all the others had internal routing):







You can find a few examples online of frames that are advertised as KG 131, but actually match the mystery frame. Only one of these (that I've found) had a picture of the inside of the left rear dropout, with the number visible (looks like it's E701315):