Originally Posted by Aeroplane
Style of BB depends on cranks. Since your bike is a trek road bike, I would say it is english-threaded with a 68mm shell. That is all the frame dependency there is.
That's what I was looking for. Thanks!
So I just get a standard 68mm english threaded BB, and the length will depend on the crank/chainring and the chainline I want.
Next question is where and what people suggest for getting such a thing. If I want a 42mm chainline, and I want to spend like $50 or less. Used is fine. :-P