Another leaking front differential breather...

Hi everyone. Long-time lurker, first-time poster here. I apologize in advance for the long post.

I see this appears to be a common issue, and someone else even made a post yesterday. I didn't want to hijack that thread, because I have some slightly different questions for the group.

Even though this appears to be a common problem on this generation, the explanations given are all over the place. I'm not sure if that's because there are multiple causes, or if it's because the root of the problem isn't really known.

Anyways, I have a 2002 Double Cab, 3.4L V6, 4WD, SR5. It just hit 122K this week. While doing an oil change Monday, I noticed that one or both of the breather tubes mounted to the inside driver's fender well had been burping fluid. I'm not sure how long it's been going on, but long enough to make a mess of everything between those tubes and the skid plate below.

I'm not sure that I've ever changed the front differential fluid. If I did, it would've been years ago when I was still using it as a commuter. (It was a commuter in its early life, but about 14 years ago my commute was severely shortened and it started only getting driven a few miles every day. It's currently used by my daughter daily, but still low miles on surface roads.)

So no recent fluid changes that could've resulted in an overfill. Also no recent 4WD use. The only change in circumstances is that my daughter just started a job that requires a 30 minute commute, and most of it on the freeway.

When I first discovered the leak on Monday, I checked where the truck is normally parked in the driveway and there were no fluids on the driveway. Yesterday morning though, after my daughter had returned home from working a graveyard shift, I discovered it was starting to leak pretty good onto the driveway.

I decided to inspect those breather plugs more closely. I pulled the plugs off and then tried testing them by blowing/sucking on the nipple. The one connected to the smaller hose, closest to the front of the truck and the one I believe goes to the ADD, appeared to be operating correctly. I could blow air through the plug, but not suck any air back in. The plug connected to the larger hose, which I believe is the breather for the actual front differential, would allow air flow in both directions. My understanding is that these should both be one-way valves, right?

Anyways, my plan is to drain and fill the front differential and replace both plugs. What I'm really looking for from the group is the part number for the breather plug that goes to the ADD. I have the part number for the front differential breather plug (

$7 90930-03136 Toyota Breather Plug - 90930-03136

90930-03136). Contrary to what I've seen others post, these plugs are NOT the same part. The nipples are different sizes to fit inside the different diameter breather hoses.

Sorry for the long post, but any help would be appreciated. Yes, I've seen the various mods of extending the breather hoses and/or using an inline filter with the element removed, but I'm holding off on anything like that until I try the basics. It worked fine for over 20 years, so...