Is there any reason why I cant fit a AU Throttle Body onto a EL intake 4lt??? I know the TPS plug is different but the wires are the same color just need to change them along with the ICS.

It’ll work. Series 2 and 3 don’t have the barb fitted for pcv. But you can work around that too.

I have the AU series 1 throttle body on my EL.
The tps is the same even the plug. It’s the ISC motor that is different even the plug.
You keep the AU series 1 ISC motor and change the plug.
Yes you don’t have the burb port for the pcv under the throttle body on the AU 1 throttle body which is better. You don’t get oil in your throttle body and inlet manifold.
I’m running a catch can. I do have the 68mm AU 1 throttle body as well.

Since I've put this up bout the AU Throttle Body I have it on there I just tapped into the wiring to suit the EL harness and also fitted the AU air duct and also used the AU breather hose that goes on the back of the rocker cover onto the air duct. And she goes really well, so thanks everyone your comments.