The square stock Toyota ones, I believe. That's what I use. He may have had to elongate some of the holes in the crossmember, Im not sure on that ,but he was able to make it work without to much trouble. Don't feel bad about using u bolts. My BudBuilt Bud B crossmember is designed to use u bolts over the frame and Ive been running it street and trail for about 5-6 years trouble free.
