how many miles should u be able to get out of the stock injectors before they need to be replaced?

Im curioud about this also. Are the lifespans different for the differnet engine models, LB7, LLY, LBZ, etc...

I did some more research on here and found it to be around 100k. I guess I'll be replacing mine.

I looked on Heathdiesel.com since that's where everyone on here seems to recommend going. But they only had stuff for trucks up to the 2000 year model. Am I missing something here?

You were looking at stuff for the 6.5 diesel, different beast. That would explain the why they only go up to 2000. I dont think people replace dmax injectors at any regular intervals unless they fail.