You can find them here: http://www.ussc.gov/Guidelines/1998_guidelines/1998_manual.cfm
Notice that 1999 is a gap year. See the archives:
Murder guideline: http://www.ussc.gov/Guidelines/1998_guidelines/Manual/CHAP2-1.pdfAsk a similar question
The US Sentencing Commission has all of the manuals on its website.
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