For those of us who bought our toothbars made by someone else (defunct Markham in my case); the fabricators usually make the mounting brackets outside edge to edge dimension about 1/4" - 3/8" less than the bucket's inside wall to wall dimensions to allow for poor measuring by the customer. In my case the tolerance was about -3/8".
Now I'd always shove a couple of washers between the toothbar and the bucket so as not to tweak something when tightening the bolts down. What a pain to line up washers with the bolt hole. The I had an A-HAH! moment of a solution that is so simple that I kick myself for not thinking of it sooner. I made spacers from scrap 3"x2"x3/16" angle I had lying around. The short leg acts as a grab handle. Knowing these things will take a beating from the dirt, I just rattle-can painted them.