I've got a '70 Charger that is missing the top stud nuts on the front shocks.

It's a future project, so I don't need the oem correct stuff.

Every time I jack it up The upper shock studs come out of their holes and get jammed up.

I was going to go to the hardware store and get some nuts and fender washers to hold the shocks in place temporarily.

What size/ thread nuts should I be looking for?