Wanna make something I can race in, and I wanna make something unexpected and utterly stupid. Something to knock beers out of hands. But I don’t know what differential gear would work best for that.

 

Are you asking ratio or brand or ?

Either way it doesn't matter, the answer would be dependent upon tire size, how much HP you anticipate, transmission, desired top speed, primary use of the vehicle and more.

 

Brand doesn’t matter. Something to fit on a 2WD 5 speed 2nd gen. Meant for highway pulls, not sure on horsepower etc.

 

Are you going for top speed? Or acceleration?

 

Has the motor been modified or are there any planned modifications for it? What about the rear tires? What size tires are you planning to run? I take it that you want beers to fly out of someone's hands from a stoplight on acceleration?

 

Your gear ratio depends on a lot of factors witch you did not list so kinda hard to answer your question. First you may want to describe "race", Drag, dirt track what?
Again can't answer your question.