944 aluminum rear trailing arm info

Okay here's the scoop on 944 aluminum rear trailing arms. First off, throw the part number, year, and model out the window. Every source says something different. It's very confusing and I've never figured out the "code" yet. The best thing to do is just look at the arm, there are two versions. In the pic attached the top version is "early" and the other is "late". These are terms I have used and may not apply. Anyhoot, just look for the arch as pointed to in the bottom arm and you'll know this is the wider of the two versions.

Early (top) will widen track by 43mm
Late (bottom) will widen track by 74mm

Credit: pics and info from the book Kafer Tuning by Helmut Horn