How do identify a T2 vs NA housing externally
 

I ran a quick search ... but is there anyway to identify it when its still in the engine (in keg form lol). Any markings, holes, etc etc

like...rotorhousings?

NA rotorhousings have the exhaust diffusers in the ports, but they can be swapped out for the smooth turbo sleeves by someone who knows what they are doing. Given the same series (s4 na vs s4 turbo) the housings casting is the same. The only difference is the turbo rotorhousings have the coolant port drilled out and a bevel for the o-ring at the LIM, and the NA housings are blank there.

Irons are obvious enough, 4 intake ports versus 6, and the hole at the top driver's corner of the front iron for the oil feed line.

thanks kevin :)