I don't think that there is one which is still active - there has been a concerted effort to cancel most of the MIL specs and replace them with ASTM/SAE where these national specifications exist.
Thanks for the quick response.
I agree, most Mil-Specs have gone that way. However, we still use the mil-spec numbers when building "Bills of Materials", finding that manufacturers still recognize them. I was told that none existed for Grade-8, but wanted to get more opinions on this.
MIL-DTL-1222 has grade 8 equivalent hex head bolts and nuts in it.
If you want something stronger, look at FF-S-86, which has socket head cap screws.
Both can be found at this link: