Modifiying my frame today for these LSx conversion mounts and was wondering if anyone has used these mounts for 63-72 GM trucks? Seems they narrowed the frame rails in 68 to accomodate big block frame stands so I need to remove about 3/8 to 1/2 inch from each frame rail and then, according to Early Classic, things will line up to fit.... I'll post again after I modify the frame with my results if anyone is interested. Pics will follow if I can size them right...