| Also known as | T1821 |
| Diagram | Fig. 7 — GEARBOX SHAFTS, BEARINGS AND INNER COVER · ref 9 |
| Subsystem | gearbox |
| Listed in parts books | 1966–1967 |
Mainshaft High Gear (20T)
The 20 tooth mainshaft high gear from the gearbox internals, also listed as T1821.
57-1821 is the mainshaft high gear, a 20 tooth gear that lives inside the gearbox on the mainshaft, shown in the parts book under GEARBOX SHAFTS, BEARINGS AND INNER COVER. This is the gear that carries top gear drive on the mainshaft side of the box. Older parts books list this same piece under T1821, so if you're working from an early catalog that's the number to match up.
Read more
Our records only show this one turning up in a single catalog listing from 1966, so we don't have a wide fitment history to point to here. If you're rebuilding a gearbox and pulled a worn or chipped 20T mainshaft gear, this is the replacement, but check tooth count and shaft fit against what's actually in your box before you order.
Gearbox internals like this one are worth inspecting closely for chipped teeth or wear on the dogs when you've got the box open anyway, since replacing one gear usually means you're already partway into a full strip-down.
Sorry if we got something wrong here. If you think this information isn't correct, .