426W Hemi 383 413 440 Big Block Header Stud Kit Bolts Stainless Steel BBM R RB Cuda Barracuda Dart - Bolt Kit for Installing Headers to Cylinder Heads - Fitment: Fits 383, 400, 413, 426 WEDGE, 440 R RB BB V8 Engines; Fits Most Short & Long Tube Headers; Will Not Fit: Exhaust Manifolds; Will Not Fit: 426 Hemi Engines. - Specifications: Hardened 304 Stainless Steel; (12) 3/8" x 1 1/2" Studs (polished); (12) 3/8" Hex Locking Flange Nuts (polished).