Square Head Bolts Description AMK Finish OEM Part # Origin AMK Part # CLICK FOR PRICING 5/16-18 X 1 3/8 SQR HD BOLT PHOS. 4 pk Phosphate & Oil (LY~) B-13361 5/16-18 X 1 7/16 SEAT TRACK STUD PHOS. 2 pk Phosphate & Oil (OQG) B-11662 3/8-16 X 3.0 SQR HD SET SCREW. 2 pk Plain Finish (KGE) 137990, 91964-S B-12557