1994 Toyota Pickup 3.0 V6 4x4 5 speed Manual Transmission R150F

The Main Point:
The transmission is blowing oil out the top through the breather port on the driver side of the stick and I'm not sure why. See pictures here: https://imgur.com/a/v8Is6X2
Here's a post I found that had pictures of the same transmission removed from the truck: https://www.toyota-4runner.org/2104216-post14.html

Troubleshooting steps taken:
I noticed the leak, put it up on a lift and tracked it down to be just from the one breather port. The retired mechanic DIY shop owner suggested putting a hose on it and extending it up the backside of the engine block. The tan tubing is what I used to do something similar in the troubleshooting process, but driving 5 miles the 3 ft tube fills and starts overflowing.

I went to the nearest auto parts store and asked about who works on import cars or transmissions specifically. The advice I got was to take some silicon and just plug it because there is (or was probably) a plate that has disintegrated over time that prevented the oil being flung up through centrifugal force out the port. I figured I'd pull my shifter off and make sure that the multiple breather ports were connected somehow just in case. From what I can tell the ports are for separate areas so I'm not sold on this idea.

For a better idea on what transmission I'm talking about here's a link to a video where a youtuber swapped in the transmission I have into an older rig: at the 1:30 mark.

No the fluid level is not overfilled; filled fill to spill from the fill port on the side. I originally did a top off when I was troubleshooting a different problem post head gasket change and discovered the transmission was low on oil, but now I've done a full drain and refill with Amsoil 75w-90 gl-4. Link to manufacturer's website: (https://www.amsoil.com/p/manual-tran...AaAs_wEALw_wcB)

The old oil was badly in need of a change and now that the oil was changed it now comes out faster. The old oil was a blackish brown with what looks like a decent amount of microscopic metal shavings for a truck with 250k miles. (pictures in the imgur album above) Tends to happen to a person new to a manual transmission, but no big chunks. Go-figure new oil has lesser viscosity than the old congealed etc etc.

I drove it very little troubleshooting problems after the head gasket change and I added 200 mL to bring it back up to full when it was about -10 degrees F in my front yard.

After those problems were fixed I noticed a burnt oil smell. I had maybe driven it about 50 miles at most since I topped it off and ended up putting an entire quart in to bring it back to the fill port level in the ~65 degreee F shop temps.

No the transfer case is not bleeding through a seal and mixing in the transmission. The transfer case is red atf and the 75w-90 is clear. Only spews clear and the transfer case oil level never changes.

Car History:
I bought this truck in March of 2021 as a temporary beater that I decided to keep as a daily driver since 19 mpg better than 12 with my F350. I'm at least the 3rd owner.

I took it to the local shop to have them do a pre-purchase inspection to see if they saw anything that I didn't see. At the time the transmission level was proper at this point at least according to their checklist. The truck has/has had leaks in most of the other fluids that I'm constantly keeping an eye on, but the transmission had no sign of a leak so I hadn't pulled the fill port screw off to check it again until 1.5 years after I had it.

The truck has zero issues shifting and I only noticed the low oil troubleshooting new sounds after I got it back from the shop after a head gasket change.

Thoughts? (besides the fact I should have figured out how to check the transmission level sooner when I couldn't find a dipstick having come from only automatics previously. >.> we don't speak of that....)

EDIT: I verified that the 3 breather ports are not connected and that plugging 1 is a bad idea before I tried that. Probably going to take it to the nearest shop to rip it into pieces because they can't screw it up worse than it is now.