94 4Runner IFS Eliminator kit...Holes for rear spring hangers?

Hey guys just want to ask a question to anybody who has done this on a 2wd. Where i am supposed to cut holes for rear spring hangers, there is what feels like tubing or some part of the frame inside. I cut off frame hole plate to get better idea, any thoughts whats there. I would like to drill out instead of torch. Any help would be appreciated.

 

i bet you could call trail gear (assuming thats where you got the kit) and talk to someone there, they do a lot of builds and are knowledgable and could help you out