1x SCL82-17 - 20x26 3rd gear OVERDRIVE
This part includes both primary and secondary gears.
This is the 3rd gear from the Overdrive set of ratios:
14x29
15x24
20x26
21x23
19x20
28x24 / 29x24
Ratios are not interchangeable between Direct and Overdrive sets.
Part no 11 in Manual page 10 (Exploded view page 3)
 
Part as photo