1963 f100 front backing plate studs?

im putting new kingpins in a orig 1963 f100 beam ... the 4 long backing plate studs are fighting me all the way to remove.. im sure im gonna need to score a new set.... anybody have a lead on were to score these by chance? its for my 61 comet gasser project.... hope I posted in the correct area........ any leads would be great.... thanx