I'd still like to see pics of how that clean up came out. I've been looking more at the long and short head tubes on prewar Cycle Truck frames; I'm suspecting, as someone else had mentioned, that the short headtube was the first 1-2 years of production (39-40). In a 1939 ad that mentions the 18" and 20" frames, it shows the bike with 3 straps on the sign board and the short head tube.
I sure wish I could some production numbers for the 20" tall frames as well as the power CT frames.
Schwinn offered custom ordered options back in those days as well as the tall frames. Who knows what other variations or one-offs might exist.
And on the serial numbers...I fear the prewar numbers will never be reliably decoded. Even the postwar numbers were known to repeat themselves 2 or even 3 times.
I've been into Schwinns all my life and into Cycle Trucks for 22+ years and I'm still learning. I'd never seen a 20" frame until last year. (I've owned a copy of Getrude Vorgang's book for 25 years with the '39 ad mentioning the 20" frame, so I knew they existed.) Then in the last year I've seen 3 tall CT's for sale on eBay. The complete blue one that a CABE member luckily got, the black frame/fork with the incorrect kidney bean sprocket and the primered bare frame with 'gussets added' which I snagged for a song and am currently repairing. (someone in the past had welded 5/8" steel plate between the seatpost clamp & the top fender bridge and the crank hanger & the bottom fender bridge!)
Regarding prewar sign boards- those lucky enough to have originals with their bikes; has anyone come across an aluminum one or have they all been steel? I've heard about thick aluminum boards on prewars.
