by the diameter of the thread area. a bolt that requires a 9/16 wrench to remove is usually a 3/8 bolt. place a 3/8 wrench on the threads to check. after that there's thread pitch (fine/coarse) and bolt hardness(grades 3-8) , the markings are on the bolt head and thats just standard bolts. i'm sure there's much more detailed info online, and this is just general info.***:D

by the width of the string range. a jolt that obliges a 9/16 torque to evacuate is generally a 3/8 jolt. place a 3/8 torque on the strings to check. after that there's string pitch (fine/coarse) and jolt hardness(grades 3-8) , the markings are on the jolt head and thats simply standard jolts. i'm certain there's significantly more itemized insight on the web, and this is simply general information

Hex head bolts, pan head, slotted pan head, hex washer head, there are a dozen different types of bolts. Nuts can be hex nuts, square, castle, WizLok, jam nuts, Nylok nuts, again, at least a dozen different types.

Grade 5 or grade 8

Depends on where the fastener came from. The dealer of the car is the best help when you need new ones.

Usually with swear words when they wont undo or go missing!!