Abu'l muzaffar mahmud shah khalji duriba bi-hadrat shadiabad // al-khalifa amir al-muminin khulidat khalifarahu and date 847 (= 1437 CE). 18mm, 8.51 grams. Hadrat Shadiabad mint. G/G #M36. 

High-silver billon tanka, excellent quality. Much scarcer than Goron/Goenka indicated.