I just got my j-spec today from japan2la who was very easy to work with and always fast to reply. The front and rear housings seem to be of different designs and i wanted to know what housings they where so here goes. where it says 13b on the front housing it is solid on eather side. on the rear the material isnt there. and above the plugs on the rear there is a cast in part that the front does not have. Thanks in advance.

 

As far as differneces in housings. S5 housings have no EGR, and I am pretty sure both s4 and s5 housings are front and rear specific.
I think mazda has changed a few tiny things on them over the years also, so it could be one housing was replaced and the other left alone.

Glen or Kevin or Neil or someone might be able to answer this a little better than myself.

-Ben Martin

 

i think that above the plug is one of those that shows if the engine has been overheated.

 

The early S4 TII motors have the knock sensor on the center Iron instead of on the rotor housing, like the S5 TII motors.. Some of the early S4 TII rotor housings dont even have the hole in the casting for the sensor to screw into. Notice the knock sensor on your motor is on the center iron.. Looks like to motor may have either came from the factory with one early style rotor housing and one late style rotor housing...or at some point it was rebuilt using whatever style of rotor housing was available at the time...

During assembly of these motors in Japan, the factory used whatever housings they had at the time of the motor build..There is a high likelyhood that the motor may have be assembled during a rotor housing production change..hence the two differnt types of s4 tII rotor housings.. When a production change happens, some of the oldstyle stuff gets mixed in with new style parts...

Anyway, I have seen it before on many motors and there is nothing to worry about..