What is the effect of a Rule 35(b) motion to reduce the sentence of convicted drug dealer John "Jock" Dickerson?

Pursuant to a plea agreement, the government filed within one year of the imposition of Dickerson's sentence a Rule 35(b) motion to bring to the attention of the court the nature and extent of Dickerson's post-plea cooperation. The district court considered the motion and concluded that Dickerson's cooperation was not substantial and did not merit a reduction of his sentence. This court will reverse a district court's decision on a Rule 35 motion only for illegality or gross abuse of discretion. See United States v. Fowler, 794 F.2d 1446, 1449 (9th Cir.1986), cert. denied, 479 U.S. 1094 (1987). In this decision we find neither.