Thanks for your replies. The first fitting was as a quick way to have two hooks on either side of the tube. I may have to weld two plates to the tube as you said overkill and drill a hole for a hook. I think I'll have to make the hinge by using two lengths of tube with one sandwiched in between and a coach bolt with some washers.

Those fittings aren't required they just would make life easier.

Btw do you guys order your steel tube for your chassis online or get it locally?