Does anybody know if flowtech headers for an 80 f150 2wd a/t 302 will fit my 85 f150 4wd a/t 351w? I need to know if they will bolt right in or if I need to do some fabrication work, and what work that might be. Also, will these make much difference for power (single to duals) for the $50 I can get them for? Thanks for the help.