I’ve recently acquired an R180 “K” differential (4.11 gear set) that has a metal breather on the top. I can’t find anything using google that matches it. Anyone know something about it? I don’t know what vehicle it was originally removed from (maybe a front unit for a 720 pickup?). It does not have a limited slip. Just curious about it as I haven’t found any information from any make/model that used a metal breather like it.

I’m really digging deep into my memory, but I believe it came from a Nissan 720 4x4 front differential. They were used to add a bit of extra durability, though I’m not sure whether they were aftermarket or original in Australia. We had a 720 dual cab as a workshop vehicle, and it was fitted with them. I remember trying to straighten one after running off the berm on a coal stockpile.

The “K” is simply a casting stamp that started appearing around 1980. I beleive it doesn’t seem to guarantee any specific configuration; most likely it’s just a foundry mark used for traceability.

All of the differentials with the K-case had four pinions, that part I’m fairly certain about, and this version would have snap-in stub axles rather than the bolted type. It most likely uses the 115 mm ring gear. Earlier units had the 110 mm ring gear with smaller bolts.

If it's from a Datsun or Nissan it's most probably this. You could buy a lot of this equipment directly through Nissan, such as vent extensions and hoses routed to higher points in the engine bay to prevent water from entering the differentials, transmission etc.

Edited January 31Jan 31 by EuroDat

Thanks, EuroDat. That’s kinda what I’m thinking too about there being a little extra durability for use on a 4x4. Thanks for the other info as well. I’m putting this “K” R180 in my 240Z and will be using a pair of “buttons” that allow the original 240Z’s stub axles to bolt onto it like the factory R180 that came with the car.