Its possible, but very, very improbable. If it has, you will smell it... gearbox oil smells like liquid arse (a delightful expression Number 1 Son taught me during his first gearbox oil change
).
The early bearings were of the open type. Gearbox oil could (in theory) flow through the bearing cage and along the shaft towards the clutch. The oil would have to have a set of mountain climbing boots, as there is a slinger ring along that shaft. The oil would flow down the slinger, put on it's mountain boots then try to climb back up onto the shaft. This would be pretty hard work if the shaft was static, and impossible if the slinger was spinning (when the car was run the next morning). Our adventurous oil would then have to flow along the archimedes screw that is cut into the shaft end (possible). Any oil that drips off the slinger or the screw flows through a drain hole in the casing snout and into the bellhousing. The oil, probably weary by now if it has escaped the slinger and screw, would have to keep flowing along the input shaft, find it's way to the clutch, then flow onto it.
If the gearbox has been overhauled, the new bearings are sealed (not open) units. It is really, really hard for the oil to get past the seals to even get a run up to the slinger.
Cheers,
Harv
