Just browsing through this parts program for the diamantes. Found a full parts listing for the 4 wheel steer system that may bolt into the magna - from the diamante. I'm way too tired to look into it further, but soo far it looks completely mechanical and no electrical to it.

The 30M has an electrical 4WS system, the ECU for it is located on the rear drivers seat backing. The suspension setup on the diamante however is COMPLETELY different - To even attempt it you would need the whole rear-axle.

yeah i noticed this in my dash, there was a spot with no globe in it, shone a torch in it and it said 4WS

It is mechanical and electrical and similar to my diamante system. You need far more than just a rear axle as there are also pumps etc used plus a pump on the trans which is why 4ws was a fwd option

my 30m does not have 4ws , must have been an option although I have only seen it on first gen diamantes