Re: what's bridge can replacement the fender mex standard?
Callaham is probably the best, and Hipshot make a nice one. There is at least one kind of Wilkinson that fits as well, I believe. Check Guitar Parts Resource (or order direct from Hipshot or Callaham).
The original Strat vibrato wins no blue ribbons, but MIM Standard Strat vibratos are significantly worse than the original Fender parts on which they're based. The metal is less durable, the machining is much rougher (the bevel is covered with lines), the saddles and screws are not as strong or durable, the thread tolerances are crappy, and the plating is cheaper. It takes Fender's original mediocre yet fairly well built design, and then cheeps it out just about to the max. Almost anything out there short of a very low end vibrato (like those on Squiers) would be better.