I did a search and never saw this question answered, the stainless kits come in button/socket head (both are alan head) or hex phillips head neither seems totality correct. which one have you tried or would be the most correct?
At bodyboltkit.com they have 6 different heads to chose from.
Shoot, I just looked closer, the dropdown list doesn't give you all 6 options. It varies from kit to kit. Well that sucks.
I wonder how much different the 48 - 50 kits are from the 53 - 56 kits. They com in the Indented Hex style...