| Also known as | T1684 |
| Diagram | Fig. 7 — GEARBOX SHAFTS, BEARINGS AND INNER COVER · ref 9 |
| Subsystem | gearbox |
| Listed in parts books | 1966–1967 |
Mainshaft High Gear (23T)
A 23-tooth mainshaft high gear from the gearbox cluster, also cataloged as T1684.
The 57-1684 is a mainshaft high gear with 23 teeth, living inside the gearbox on the mainshaft assembly. It's part of the cluster that rides along the gearbox shafts, shown in the parts book under the gearbox shafts, bearings, and inner cover section. In older parts books this one was listed as T1684, so if you're working from an early catalog and see that number, it's the same piece.
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This gear works as part of the top-gear engagement in the box, meshing with its mating gear to give you high gear drive. Catalog entries for this part run through the mid-to-late 1960s, so it shows up on gearboxes from that era.
If you're rebuilding a gearbox and pulling the cluster apart, it's worth checking the dogs and the bore for wear before deciding whether to reuse this one or replace it. Bring in the old part or your gearbox number and we can help confirm you've got the right gear for your box.
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