Standard header bolts, from Trans-Dapt Performance Have a 7/16" head size for use with headers. For even tighter fitting applications, use Trans-Dapt's Small head bolts with a 3/8" head size. Grade 5. Click on the MORE INFO tab below to find out more...
 
Part # ProductTube DiameterTube StyleFinishLengthMaterial Media
4025 HEADER BOLTS; 3/8"-16 x 3/4"; Standard Head (12 bolts) 3/4"
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$4.51
4900 HEADER BOLTS; 5/16"-18 x 3/4"; Standard Head (12 bolts)- SB Chrysler Black Oxide3/4"Grade 5 Carbon Steel
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$3.70
4904 HEADER BOLTS; 3/8"-16 x 1"; Standard Head; Thick Flanges (12 bolts)- SB Chevy, BB Chrysler, Pontiac Black Oxide1"Grade 5 Carbon Steel
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$5.09
9943 HEADER BOLTS; 3/8"-16 x 3/4"; Standard Head (16 bolts)- BB Chevy, Ford V8 Black Oxide3/4"Grade 5 Carbon Steel
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$5.74

Standard header bolts, from Trans-Dapt Performance Have a 7/16" head size for use with headers. The smaller head size allows for additional clearance around header tubes or sparkplugs. For even tighter fitting applications, use Trans-Dapt's Small head bolts with a 3/8" head size. Grade 5 hardness

 
http://hedman.com/images/ePIM/original/4025-D.jpg
http://hedman.com/images/ePIM/original/4900.jpg
http://hedman.com/images/ePIM/original/4904-G.jpg
http://hedman.com/images/ePIM/original/9943-076.jpg