Tim Neenan just said the early Sequoias were built by 3rensho. It would be just in 1981 and I think part of 1982 they were built. Once the Miyata made Expedition came out the geometry of the Sequoia was changed, as well as the manufacturer (probably Miyata). Allez SE's were also made by Miyata, starting in 1984. Top end Allez's from 1984 were 3rensho built and a few details from earlier ones changed (campy dropouts on 1984's). In regards to Sequoias, the 3rensho ones were a deeper blue color and had fully chromed forks underneath the paint. They also had longer wheelbases for touring, and more rake to the fork. Most likely no serial number on bottom bracket of 3rensho Sequoias, just the size in CM. Look on page 2 of this brochure to see a 3rensho Sequoia: http://www.specialized.com/OA_MEDIA/pdf/Sequoiabro.pdf
yes, its a very small image.