They changed the output in 2001 from 215 to 235 and a High Output (245hp) version was also released for 01-02 but those only came in 6spd trucks. The 98-99 trucks came with a more aluminum whitish colored valve cover, and the 2000 and up came with a black color. thats all. My 2000 has the black valve cover and is factory rated at 215hp. Where the 20hp difference in the Standard ouput (S.O.) comes from I'm not sure. I don't know if its a difference in injectors or possibly a different ECM fueling algorithm. The 245hp H.O. has a lot of differences including injectors, injection pump, pistons and higher compression. If you're looking to modify your truck the S.O. is a much better platform to start from than an H.O.
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