"U" nut for mounting over sheet metal edge.
Various mountings GM/Ford.

Fits Screw:
378178-DB( front fenders)
379156-S2
379156-S2-HTS
378178-S2
9756
All with thread 5/16"-18.

GM number 1495258

Panel range: 0,025" - 0,150", (0,6 - 3,8mm)
Center, or hole to edge: 27/32" (21,5mm)
Phosphate (black).