Posted 5/27/2023 12:35 (#10245804 - in reply to #10245136) Subject: RE: Semi fifth wheel replacement
The description of the "frame bolt" link you show says they are called "hex flange screws", and get the name "frame bolts" only because they are often used on truck frames.
They are not serrated as you suggested, and are available in either black phosphate finish or a bright finish.
The specs of the "flange bolts" you show are essentially the same: both grade 8.
The "frame bolts" you say are so expensive compared to "flange bolts" are actually cheaper than the "flange bolts" you show.