The mercury ring replaces the "part the truck came with" it is just thicker metal with a nice inside lip, easier to weld in, and yes, you have to install the lamp bucket..the original one.....from the back.
And here's a pic of a converted bucket, see how the nuts are welded . So you can adjust the light from behind?
I did mine a little different, I just cut a slot in the back of the original adjusting screw, so a flat tip screwdriver will fit, then just drilled a hole in the bucket to line up. I just turn the original screw from behind, and I can put a plug in he hole, so nothing gets dirty. I'll take a pic....
