Frame Control Hole Description
WARNING: This page is about a different car, the 2003 GMC Safari and 2003 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Control holes are round or oval holes located in the underbody structure sections, the upper body, and the body sides. Some control holes can be identified from other holes by a turned up lip on the inside of the hole. This reinforced lip reduces the possibility of hole distortion and increases accuracy during assembly. Utilize control points whenever possible when measuring underbody dimensions, in order to obtain the most accurate readings.