[FirstOwner69]

As Lefty said, there is no standard. So, do whatever suits you. As an example, number them as a reference. #1 could be from the front bumper to the front cross member. #2 could be from the front cross member to the firewall/front of cab. #3 from front of cab to back of cab. #4 from back of cab to rear axle. #5 from axle to rear bumper. You can then assign letters within each section if desired. As an example, 1A could be the core support location. Draw sketches if it helps for further definition.