Normally there's a Aluminium bearing on the shaft, most of the time its CastIron though.
There's Aluminium cast into the motor part of the shaft, the cylindrical chunk on its centre.
The pistons often got a Aluminm conrod or end cap and sometimes there's a Aluminium 'oil scoop' pickup on the end of the shaft held on by a tiny grubscrew.



I have separated them, but the noise, hard labour, blood sweat and tears made it not worth it.
Irony, Aluminium.