I just picked up a 1983(?) Sekai 4000 off of CL this afternoon. It's in great condition with just a little dirt, grease and paint chips. I'll get photos after I clean it up and it stops raining (so July maybe!). I was surprised that it was Tange Champion #2 tubing, does anyone know when they changed over from #1?

Sekai 4000
58 CM CtT
Color; Dark Silver
Frame; Tange Champion #2
FD/RD; Suntour Cyclone M-II
Crankset; Sugino AT w/2 rings
Serial # on BB; M3C05037