Race cars generally use one of four basic types of differentials:
BTW--the little 210hp FR2.0 just about matched the XFinity car times at Martinsville!
NOTE: You will find that many drivers will run a much "stiffer" rear--with 900# springs and quite a bit of ARB. This makes the car quite "loose" or oversteery----so they offset this by increasing Diff Preload to 40+ and change ramp setting to 65coast/70 drive. These same drivers tend to run much less front brake bias.
My personal view is much of this driver preference has to do with how they trail brake. Normally, higher Diff Preload can be run with a heavy trail braking technique, but lower front brake bias makes trail braking more difficult. So this "stiffer" set up preference is generally a desire to rotate the car during corner entry without trail braking.