Looks like I spoke to soon, without checking my memory or the facts. My book doesn't show a breather on those 3spds and it's been thirty years since I've had one apart. The original 3 spd for my '67 did have a breather on the top of the tail housing. It's the later all-syncro type.
You mentioned a 1/4" hole and the oil slinger. Is there a slot on the bearing retainer(nose cone) that lines up with a hole under the bearing? The oil thrown off by the slinger should return to the trans through that hole.
Checking the crank end play without a indicator??
If the thrust bearings are really worn and we're talking about a runing, but semi tired six then you can try this. With the fan blade, turn the engine forward, then back. The cam gears are cut at an angle. The valve springs will try to keep the cam from turning. The crank gear will walk up and down the taper on the cam gear and push the crank in and out. If the engine is gummed up or locked up or the end play is within specs, you won't see anything.
