| Diagram | GEARBOX SHAFTS, BEARINGS AND INNER COVER |
| Subsystem | gearbox |
| Listed in parts books | Not catalogued by year yet |
MAINSHAFT c/w THIRD AND LOW GEAR
Gearbox mainshaft assembly supplied with third and low gear fitted, PN 12277.
Part number 12277 is a gearbox mainshaft that comes complete with third and low gear already fitted, as shown in the parts book under GEARBOX SHAFTS, BEARINGS AND INNER COVER. This is the shaft that carries the sliding and pinion gears inside the gearbox shell, and having third and low supplied together with the shaft saves you the trouble of sourcing those gears separately or trying to match wear patterns between a used shaft and used gears.
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The Lucas tag on this one doesn't match up with what it actually is - Lucas made electrics, not gearbox internals, so treat this as a mechanical gearbox part rather than anything electrical. Our records show it appearing in gearbox figures across catalog listings from 1967 to 1969.
If you're rebuilding a gearbox and pulling the mainshaft assembly, it's worth checking bushes, bearings, and the mating gears in the cluster while everything's apart, since you're already in there. Call the shop if you want to confirm this is the right shaft assembly for what you're working on.
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