We need:
1. BB shell width (probably 68 or 70mm)
2. BB shell threading (35x1 RH, 35x1 LH, 36x24 RH, 1.375x24 LH)
3. seat tube OD (28.0 or 28.6mm)
4. seat tube ID (25 to 27.4mm)
The bridge across the seat stays looks like a Pletscher mousetrap rack mount, something one would see on a low-end frame or perhaps a touring bike.
__________________
"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069