Guadalajara, 1867, 1r black on gray blue, in combination with 2r black on green quadrille on 1867 folded letter to Zacatecas, tied by neat Guadalajara oval date stamp (Schatzkes 295) with second clear strike at left, Very Fine, only 10-12 covers are known bearing the 1r gray blue. Scott No. 2+13  Estimate $400 - 600. $0 (Image)