Conspiracy to Possess with the intent to distribute crack cocaine is found under 21 United States Code Section 846. Depending on the amount of "crack" or cocaine base the penalties can differ. Certain amounts can trigger a mandatory minimum prison sentence. The penalties can be found under 21 United States Code section 841.
21 U.S.C. 846 is the statutory citation for Attempt and/or Conspiracy for an offense committed in that subchapter of (related to drug offenses) and basically says the penalties are the same as those for the actual offense that was the object of the attempt or conspiracy.
21 U.S.C. 841(a) prohibits distributioin or possession with intent to distribute controlled substances
21 U.S.C. 841(b) sets out the penalties. 841(b)(1)(A)(iii) establishes a 10 year mandatory minimum for 280 grams or more of cocaine base (crack); 841(b)(1)(B)(iii) establsihes a 5 year mandatory mimimum for 28 grams or more but less than 280 grams of cocaine base (crack). Less than 28 grams there is no mandatory minimum, zero to five years..
Within these different statutory ranges the Sentencing Guidelines suggest different sentences for different amounts, and a whole lot of lawyering by an experienced federal criminal attorney goes into getting great results that are better than what the guidelines often suggest.