Have a 99 Superduty , standard cab that has lost both nerf bars due to rocker panel rust. I am searching for a Frame mounted step or bar to replace these.Has anyone found steps or bars that are frame mounted? Or is custom fabrication my next move...

 

I would guess that frame mounted steps won't flex with the body and may rub/break, so you probably won't find any online. Most likely have to build your own.

 

I know I'm months late to the party, but if you're still looking for a solution, especially for a '99 regular cab, look here:

https://www.summitracing.com/parts/dzz-370303/overview/

 

I put on a set of these and they are very sturdy -