To me they look to have a differently shaped edge and the 70 may be wider at the "thickest" point. You might be able to add some metal to the 69 then reshape, work both sides and then add the cut outs.
Not sure if other sections of the supports have different openings, holes and such. At least some of them are though that could be addressed also if you could identify them all. Also you would want to check to see how they attached the replacement support and if that will need to be redone anyway to replicate the factory looking methods of attachment