Still the wrong thread
This is for regrouping on one page vehicles that are similar/identical (usually background).
The thread you need is that one:
https://imcdb.opencommunity.be/index.ks?page=forum_topic&id=7034&index=0
The reason why there is a separate thread is because I don't apply these the same way (mass update is not done via admin pages of the sites, but directly on the database), so it is easier to have these two tasks separated.
But for this case, I don't really see the point of having that more specific GP7 chassis code, it is better to have a generic GP for all of that generation.