I cut up another bracket and welded a piece of it at the right spot on the first one. The alternator fit without shims and the original slots allowed for fore/aft adjustment. In the process of fitting various reman GM alternators over the years, I've discovered that they vary in thickness at the mounting boss by enough to require either washers or the judicious use of a file to make them fit. One time I did get lucky and it was spot on and the same as the one for which I made the bracket.
