This might be a rather tough question, but does anyone know the reason for the difference between these two seat hinge bolts? When I took the seats out of my '70 Challenger and took the backs off the bottoms, I had a mix of hinge bolts (something that was done by the prior owner). I had what I believed to be one correct bolt (see photo in first post). I received three used bolts yesterday from someone who restores seat belts and their bolts. He said he took them off of a '70 vehicle with high-back bucket seats. In the following attached photos, one of his three bolts is on the left, and my one bolt (that I believe to be correct) is on the right. His "shoulder" is 5/8" high, while mine is 1/2" high. His is stamped with the letter "N", mine has an "SB" cast in the head. Were these bolts used in different model/year Mopars? Are either one of them correct for a '70 Challenger with high-back bucket seats? Also, I had what I believed to be one correct washer for the hinge bolt. It is steel and slightly concave and measures approximately 1-1/2" diameter x 3/32" thick, with a 1/2" center hole. The gentlemen was kind enough to send me three "washers" as well (says they were also from a '70 vehicle with high-back buckets). They appear to be made of a "fiber" material, and are completely different in size. Which type/size of washer was used with the hinge bolt on a '70 Challenger? My steel washer looks to be correct and functional, or is the fiber washer correct? I know that these bolts and washers were used in many of the models during that era, but any knowledge you can share about the applications for these is greatly appreciated. Thanks.