Tring to do a bit of reasearch . My former 1970 challenger ( Dec 1969 LA plant build )had the smaller ( 5/16' ) hex screws with a 3/4" washer diam. retaining the rear inner fender splash shields
Yet it seems 1971 and later seem to use the larger ( 3/8" hex ) washer screws eith a 1.25" washer diam.instead
anyone have a 1970 with the larger screws as original?