| Also known as | T3994 |
| Diagram | Fig. 8 — GEARBOX SHAFTS, BEARINGS AND INNER COVER · ref 13 |
| Subsystem | gearbox |
| Listed in parts books | 1970, 1974 |
Mainshaft 2nd gear (21T)
The 21-tooth 2nd gear for the gearbox mainshaft, PN 57-3994, formerly 57-1922.
This is the 2nd gear that rides on the mainshaft in the gearbox, a 21-tooth gear listed in the catalog under the GEARBOX SHAFTS, BEARINGS AND INNER COVER figure. It's part of the gear cluster that lives inside the gearbox shell, working alongside the layshaft gears to give you your ratios.
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The older factory number for this same part was 57-1922, so if your parts book lists that number you're looking at the identical piece under its earlier designation. It also shows up under the legacy T3994 form.
Our catalog record shows this appearing across a couple of gearbox listings from the early-to-mid 1970s, but we'd rather you confirm exact fitment against your own gearbox before ordering than guess from a year range alone. Give us a call if you're not sure which cluster you've got.
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