I just purchased some grade 8 1in 7/16 bolts with washers and lock washers along with lock nuts do you think this will work for my bumpers as a body man I dont see them loosening up but I dont have those washers imnot restoring the car right now, im just trying to drive it over the winter ot will receive more tlc

 

For around 32 bucks you can get the entire set from opgi. This includes the special washers. IMO grade 8 is a little excessive for this application. JMO.

 

They'll work as long as you don't use the jack to lift the bumpers. I can tell you from personal experience they DO allow some movement of the bumper braces even if they're done up snug.