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Just wondering about the RX, turbo Vortex and mpfi gearboxes of the L series and their 25 spline front axle stubs with 25 splines....what about the rear diff splines where they normally 23 spline on MY and most L's and upgrade to 25 spline on the same models that got 25 spline front stubs ??

On my mpfi touring wagon the front stubs are 25 but on the rear diff i used normal l series shafts, never counted them but i guess they are 23. Anyone know why they used 25 spline on the mpfi box? are the internals any stronger?

I believe the EFI EA82 made more torque than the carby versions and the wagons would have had a little more weight to drag around in mostly FrWD mode . Had they been AWD they would have had the torque loadings reduced by sharing it with the rear diff and wheels . From memory early AWD non turbo Libs used the smaller front stubs for this reason , the 2.2L FrWD and 2L turbo AWD versions used the larger 25 spline stubs because they needed more strength in this area .

A .

Well, found out the dirty way - 23
Also found that most L's and MY's would have rear diff breather absolutely caked in crap by now so the only way they can breather is blow it out the seals

so begs the question if AWD having 25 up front got 25 at the rear.
Inside the L boxes I have pulled apart the inside spline at the diff is 25 with the outer stub step down to 23

Nope, all rear diff output stub shafts are 23 spline count. Dunno why they made the difference between the two, there's no shaft thickness difference, just spline count

Cheers

Bennie

I'm pretty sure the EFI (both turbo and non) use the larger front inner DOJ due to the torque differences.

As for the rear they only get 40% of the torque so no need to manufacture 2 different diffs for the one model.

This does change for the later STi and 6cyl models but these have internal stubs.. front and rear.

What are you trying to achieve Jonno?