Gator is correct. The cars built about midway through the 2001 run started getting the Ls6 style intake and the cam was a touch different. The 2002 got that plus a better exhaust manifold design. 98-99 are the weakest if you consider 290-310 HP at the rear tires weak.

 

01+ had stronger rod bolts if that means anything.

and Gunflinger....00+ had better manifold design.