This was the basic shock tower. 3 mm.
Xtreme racing makes a nice 4mm one that has multiple holes that I think could be used with gullwing or flat w/o having to change shock towers. About 20 bucks. You will need the aluminum shock mounts from and exotek or STRC shook tower. Good luck dremelling. I bolted
my ST shock tower to it to use as a template when dremeling the base.
Edit: just thought of this that you need to drill the wholes a little larger for the shock attachments. So maybe the Xtreme ones wouldn't be good because of lack of material. Just find thicker b44 ones.
http://https://www.amazon.com/photos/share/LoPy6qUWffYgglRX1nv6qF9CBjpAkIC5ver81TzaCye