does anyone know about porsche 944 rear suspension

[1303mark]

what year did porsche change to using aluminium rear trailing arms in the 944 suspension.

i would like to get hold of some kit off the older steel arm setup, but i dont know which year they changed.

when i enquire at places all i know is that i need to have the steel arm parts, but that doesnt help me with which model - year they should come off.