Can I use an s4 center iron in place of an t2 iron???
 

My center iron has a small chip on the surface but the housing covers the chip when place together. No contact with rotor whatsoever. Only with the water seal. Will I have a problem with this or can I use my spare na center iron? Need help I've tried searching already

a chip? is this one of cases where the seal track has eroded or broken? a photo might help others help you.

the N/A will physically bolt up to the engine without issue. however, you'll want to double check if there will any issues with the EGR system (if you plan to keep it functional) and also port timing as i think there may be slight differences. neither would keep the engine from running, but is worth mentioning simply FYI.

Just realized it's the rear iron with this. My bad

middle iron yes, ( though NA is smaller port and top style ACV )
you will need a ACV blanking plate ( a thin one ) on that center plate

rear iron.. no .. porting is hugely different to t2 ( 6 port and 4 port )

get another T2 plate,, preferably a s5 iron with larger support area around the rear dowel