[4BYnTacoma]

What is the hose size to do the diff breather extension?

 

[mudferret]

What is the hose size to do the diff breather extension?

1/4" (rubber fuel line)
Best to buy extra if you plan on running it to the engine compartment. I needed 13' since I left plenty of slack at the axle, and looped the fuel line in the engine bay (to minimize any potential for water intake). Also added a Fram G1 fuel filter to the end of the hose to maintain zero pressure in the diff.

 

[4BYnTacoma]

Do you happen to know the part number for the "thingy" that goes in the diff that you attach the hose to. My dealer couldn't find anything...

 

[afcajun]

I just finished my diff breather mod and all i used was a coupling you can find at any auto parts store. Just get the 1/8" NPTthread side to a 1/4" hose fitting. Got mine at NAPA.

 

[Intrepid]

part #'s

Instructions and part numbers

I actually just did mine two weeks ago when I changed the diff's, tranny, and Xfer case fluid to amsoil, I have been thinking about it for a year and just never got around to it. Those parts worked fine.
Just for reference the union was $6.92 and the breather plug was $3.34.