yeah i would think Dagree is right they are chrome plated. a mate at work has a GME one bolted to a galvanised bull bar for the last 10 years and no problem. also think you would be right with the stainless steel bracket as i had a look on google and it also has a lot to do with surface area as well and since there would be min you should be right. i personal would try stay away from welding to the gal as you don't want to brake the coating. even tho you will give it a good paint job, welding would burn the gal of on the inside and it would rust from inside out. i always try to bolt
