I'm the Wiz, and nobody beats me!
@GTs58 I am still trying to find some clarity on year of this frame, if that is even possible and Schwinn using the number multiple times doesn't help. With the SN (B58705) on the BB, the fat bar frame, @Obi-Wan Schwinnobi mentioning it might be a '47, I am confused to say the least. Can you help Wiz?
The first pre post war & post war serial number prefixes used starting in 1945 were H I J K. These were also used prewar and war time. They are not left overs, frames or otherwise. Then A B C D and E into 1948. There were also a few other letters thrown in here and there to make things interesting. I going to say your serial number was stamped in 1947.
Check out Obi-Wan's post #3