Need Help on the Rear Differential Breather Mod

I bought all the parts for the rear differential breather mod, and tried to get them installed today. However, I ran into a snag. It appears that the union part that threads into the differential housing had the wrong thread size, such that the upper threads ended up stripping out, but the lower threads were fine. I did wrap the threads with Teflon tape. Basically, as I was screwing it into the differential housing, once the threads bottom out, I was able to keep turning the union with moderate torque on the wrench. Realizing what was happening, I remove the union and put the old breather back in. I was able to torque the old breather back to its original torque (i.e. crank on it).

I bought the part on Amazon, and it said it was a genuine OEM part, number

$8 90404-51319 Toyota Union - 90404-51319

90404-51319. The part looked like the picture. The questions and reviews indicated others were successful doing the mod on their Tacos using this part.

Is the part number correct for a Tacoma? I know that the thread pitch for the breather is somewhat unique (i.e., BSTP 1/8x28 tpi).

The packaging for the part is not what one would normally get from a dealer. I suppose it is possible I got a counterfeit part. The odd thing is that this is supposed to be a tapered threaded part. Yet only the upper threads on the union were stripped, indicating the union threads on my part had too much taper (the lower threads were not engaging fully). So maybe a manufacturing defect, or maybe the metal was really soft and its the upper threads that go first.

If part no. 90404-51319 is correct for a Tacoma, I'll just go to the dealer and order the part to make sure I am getting the real thing. If this is the wrong part, I would be interested in knowing what part I should get.

 

I ordered that same part from Amazon in February and didn't have any issues with my install. I didn't use a torque wrench - just a regular open end wrench. How big was the wrench you were using and is it possible you stripped it by over tightening it?

 

I used a open end wrench. I never felt that I put that much torque into it. I did have the threads well wrapped with teflon tape, I wonder if that reduced the friction enough for me to not realize how much torque I was putting in. The metal does appear soft thought.

 

I bought mine from toyotapartsdeal.com

https://www.toyotapartsdeal.com/oem/toyota~union~no~1~90404-51319.html

This and the Amazon part are both the same part as shown, and worked on my truck too.