I did it to improve the silhouette and proportions.Thanks for the pictures @agonistes86.
You sanded the body, exchanged the original thicker arms, then.... bulked up the new arms again? Why?
Thx.
The original body (for some weird reason) has wider upper arms than deltoids. That means the upper arms stick out more than the shoulders, which really messes with the silhouette. It's just not how the human body works.
Below I included a shot of the original body. Look at those arms - it looks so weird and unnatural. I first tried modifying them, before finding the other body in my parts bin and realizing that "HT slim body" is not actually one type, but there are various iterations.
The new arms are better in that regard with proper shoulder bells, but the upper arms were rather thin without definition. Since the black jumpsuit is very form-fitting, and I re-tailored it to be even tighter (after the sculpting), having the arms properly proportioned really sells the final look. If the arms are too slim, the fabric creates unnatural folds.
So I took some screengrabs and compiled references from Dagobah to get close to Hamill's physique. I know it's the wrong movie, but I don't expect his physique changed drastically in those 3 years.
Here's the original body, the movie reference I made and the final result. For reference, I also increased the neck length for better proportions.
I've since upgraded the sculpt to the Mando version.