Background
After the truck bed assembly is installed with all supporting braces and plates, the front wall is reinforced with fasteners including 8M flat head bolts. The flat head bolts are designed to be flush with the top surface, and to accomplish this, the hole must be bored to match the profile of the bolt head.
Metric 90-degree countersink drill bit
The metric 8M flat head bolts use a 90-degree taper (SAE bolts are 82-degrees) that requires a countersink drill bit with a wide enough diameter to enable a flush mount.
