Another thing to consider, and I’m not an engineer, is bolt stretch, possibly better defined as stress or fatigue. I realize high torque is what stretches them and in the case of fender attachment might not involve high torque, but it’s worth considering getting new unused bolts.
1957 Chevy 3200Daily DriverPS, A/C, Tilt column, Rebuilt 350, Rebuilt TH350, Reupholstered Bench Seat, sound proof/insulated, LED headlights/taillights/backup lights/interior courtesy lights.
Follow in the DITY 
