well, what Wash was saying is that building a 308 AR and having it work the first time you pull the trigger with no issues is hard enough with buying a stripped lower that is complete, so doing the first one as an 80% just makes it a lot harder to figure out the initial issues. Unlike the AR15, there isn't a perfect mil spec standard for these, so there are variances manufacturer to manufacturer. So far as uppers, any upper that fits the DPMS LR308 pattern should work, excepting possibly palmetto state armory's (PSA). their 308 AR stuff looks to be a mess so far. The standard DPMS upper is available pretty cheap, I've seen it below $100 lately. i'm assuming you'll want to assemble the upper yourself.