Conversions & Hybrids - gm pcm?

is there any difference between the stock pcm?
different years ?
is there one that is sought after?

Yes there is a difference 97/98 are the same as well as 99/02. Im not sure about the other years. 99up pcm’s are allot easer to tune.

Thanks 88s10, I Apprecate You Reply And The Info