Ball Joint Hardware

[NvrDun71]

Was doing a front end nut and bolt check the other night and managed to snap 2 ball joint attachment bolts in the process. Strangely enough the GM service manual calls for 25 ft lbs, but it snapped with only 20 ft lb. Anybody know the torque spec for these bolts? I'm assuming basic grade 8 hardware is acceptable here? They appear to be black oxide grade 8 1/4" fine thread w/ a metal lock nut, but just want to verify what is correct for the application.

These are on DSE arms for 67-69 Camaro/68-72 Nova's and are stock replacement Moog ball joints. Any help is appreciated.....