If all you had to go on was an assembled shortblock how could you tell by the irons and housings if it were an S4 or an S5 TII engine?

(Excluding any obviousl clues on the front cover)

Im looking at a shortblock a guy is selling locally (for basically nothing) and I am trying to tell if it is and S4 or S5.

I know the front cover is an S5 because of the OMP. But i think it might be a mix of other parts from an S4.

 

S4 has the knock sensor on the centre plate under the oil filler; S5 has it on the front rotor housing above the spark plugs.

 

Thanks NZ, once again!