Welcome to the forum.
The breather tube is the most likely culprit if it's not leaking oil. I know you said it looks good, but I'd replace it if I were you.
There are two press in seals where the CV axles go into the front diff. They aren't expensive. You could replace those for peace of mind. You have to pull the a/arms and knuckles off, pull the CV axle, then pop out the old seals and install the new ones with a socket and hammer.
And to add to what Mac said, there's a speedo sensor on top right in the front, and another on the pinion housing coming out of the back of the front diff. Check those.
The breather tube is the most likely culprit if it's not leaking oil. I know you said it looks good, but I'd replace it if I were you.
There are two press in seals where the CV axles go into the front diff. They aren't expensive. You could replace those for peace of mind. You have to pull the a/arms and knuckles off, pull the CV axle, then pop out the old seals and install the new ones with a socket and hammer.
And to add to what Mac said, there's a speedo sensor on top right in the front, and another on the pinion housing coming out of the back of the front diff. Check those.
