I know t2 and n/a starters are not compatible because of housing differences. But will an s4 n/a starter fit in an s5? What about s4 t2 in an s5 t2??

 

S4 NA and S5 NA starters are interchangeable.
S4 TII and S5 TII starters are interchangeable.

 

Thanks a bunch!

 

Also I might add: S4 auto->S5 auto->S4/5 TII

 

wish i knew the autos were interchangable with a T2, i grabbed an n/a 5 speed starter at the wreckers only later to find out it wouldn't work but there was an n/a auto there as well which would have worked.

i wound up ordering it and had to put it out of comission for a few days.

 

The auto starters are supposedly a little stronger too because they have to turn the torque converter also. That is what I have read here on the board.

 

Correct, they are 2.0kW instead of the manual's 1.2kW.