I just got my inner rockers from TABCO and them measure 40" long x 6" high. 3 5/8 then a 90 degree bend, 1 1/4 then another 90 degree bend the opposite way leaving 1 1/8. I had to trim some of the edge by the cab corner, but I opted for the longer length so I could trim if needed.
Hope this helps
https://tabcoparts.com/1234-41798.html