IMOP one of the small things that gets missed frequently is the OEM vent for the axles.
I’ve learned over the years the best thing to do is eliminate them all together.
I remove them and extend the line utilizing a 5/16 fuel hose up high in the engine compartment.
They are a failure point on...
Depends where you live.
If you live in the rust belt or drive your rig in the winter where salt and other ice melters are used then the lack of excess grease will lead to corrosion and pitting of the surface.
Then those polyurethane seals will not provide the seal that the felt seals will...