The AUSubaru.com.au Forums

Would it be possible to fit a 4 speed automatic out of say a liberty and into a carby l series?

not without a lot of work. The 4EAT was available on later model turbo efi L series, but not in Aus. Some vortexes may have them, they are again EFI.
I'm not sure about the Vortex, but the L series had a separate computer to run its gearbox. From the Liberty onwards, the auto was run by the engine's ECU.
If you're going to swap the box, you'd be better off doing the engine swap also at the same time. It'd be easier.

Ahh OK might as well wait till ej22 time

The 4EAT in any model subaru has a TCU to control it, this in turn interacts with the ECU.

It would be way easier to get the 4EAT + TCU, EJ motor + ECU and matching differential (plus other needed bits like the shifter etc) and install it all at once.

TOONGA