I've had a Ralliart for a year and this is what I've found out.
The SST gearbox hardware is the same, however Super Sport software mode is not enabled. The transfer box with ACD is the same, not sure about prop shaft. The rear diff is completely different as it goes without AYC. The pump is different as it only controls the ACD, there is no AYC, so has fewer valves.
The front and rear suspension is completely different as are the hubs, drive shafts and brakes.
The engine is the same except different air intake, milder cam shafts, plastic not metal BOV, completely different boost piping, intercooling, smaller single scroll turbo, different water & oil lines & exhaust manifold/downpipe/exhaust system. As far as I know the complete fuel and ignition system is the same?
So yes, the basic engine (exc cam shafts) and gearbox are the same, so could be used to repair an Evo X. But the rest is no good. If you're looking at the cheap Cat C Ralliart with LPG conversion on Ebay, I noticed that too!
Alistair