Gen 3 axles are larger diameter, so you can't simply swap in a Gen 2 axle.
As for the Gen 2 Akra, to get it to fit, he had to fabricate a replacement bottom frame cross member as well as a shorter dogbone, because otherwise there isn't enough clearance. A longer radiator bracket also had to be fabricated for header clearance - take a close look, the radiator is sticking out further forward (he blocked off the gap with panels).
As for the Gen 2 Akra, to get it to fit, he had to fabricate a replacement bottom frame cross member as well as a shorter dogbone, because otherwise there isn't enough clearance. A longer radiator bracket also had to be fabricated for header clearance - take a close look, the radiator is sticking out further forward (he blocked off the gap with panels).
