Why do my two e30 m42 Getrag 240s have different size input shafts?

[irish44j]

I have a pair of G240 trannies that both came attached to M42 engines. The part numbers on the side are the same, and they are IDENTICAL in all respects on the outside.

But then I found a difference: The input shaft diameter is not the same on the two of them (and the pilot bearings on the two engines are different sizes).

They also have different numbers around the lip here, but that looks to be a serial number not a part number.

So.....anyone know why I have two G240s, out of two M42 e30s, that have different shaft sizes? I'm inclined to use the one with the larger shaft (since one would think that it is a newer/stronger model), but wanted to check here first and see if there was another explanation for this.

pics:

visible difference!

[jlevie]

Early vs late production for 318is cars. The transmission with the smaller input shaft was used up to 9/90.

[irish44j]

Thanks Jim, that's what I figured but wanted to make sure someone hadn't swapped shafts or something else odd. So confirmation is good.

For a second I really hoped that somehow I had a ZF e36 M3 tranny there, until I looked on the side of it :(