Engine rebuild kit???

Another round of mods for me. Its tax return time. I was going to stroke the block out of the '99 that I am parting out, but the wifey is allowing me only $3,000 from the return. I could do the stroker, but there are other mods I was wanting/needing to do. So I decided to save some cash and just rebuild the '99 block and throw that in there. I have been searching for engine rebuild kits and finding a bunch of year blocks that they are offered in. Whats up with that? some say '91-95, others say '96-'98, and some places dont offer kits past '95. These kit dont have any sensors, just pistons, rings, berrings, gaskets, oil pump, timing, and seals. All of that should interchange. Why all the different year ranges? some offer cams for the earlier year kits and say no cam available for the later years. Did they change the cams in the later 4.0 because of the emissions changes? My brain is fried:gee:

bump? anyone???

i do know that the piston ring size did change in 96 but is the kits come with pistons so i dont understand why that would matter. they would just have to match the rings to the pistons. i seem to remember something about a cam change but not sure. maybe you could call one of the companies that carrying these kits and ask them. then fill us in.