Stamped sheet metal tube intersections? Alignment nubs with brazing in them?
Serial number
"4". There are splayed and swaged tube ends inside the bottom bracket and head tube.
Sheet metal brazed joint?
1/4-24 threads and lots of brazing metal. I wish I could have watched them sand blasting
looks like formed sheet metal to me
the upper part of this tube joint looks to have an alignment nub for fitting the tubes to the tube intersection
there are very faint braze joint lines. Head tube and bottom bracket have brazed in "doublers"
closeup of seat tube with brazing joints. looks like preformed joints with possible furnace or dip brazing
top tube measurement and braze joints
seat stay
rough measurement of chain stay
It looks like the head tube was formed from sheet metal and wrapped (brazing joints again)
there is a frame doubler about 5-1/2" down in the seat post tube
what is the distance between the two bars? It may be a Mead, Schwinn or even a Shelby.
Here are some pictures I took, some with a ruler