Broken Diff

Gears are important too. Racing gears are softer so they don't break teeth on the initial shock like a trans brake and slicks deliver. Street gears are harder for wear properties but don't hold up as well at the track.

Yeah...good point.
Long life would mean hard and brittle but not so good for shock loads.
The gears i broke were original Chrysler gears.

So...does anyone know what brand would be best?

I've seen USA Standard,Yukon and Motive.
I know richmond make gears but haven't seen a reference to 3.73 ratio yet.