I tried searching I couldn't find a definitive answer. My outers are starting to rot out but the inners appear to be fine I hit them with a screwdriver and they feel solid. I will replace the outers at some point but I want to know if it's still safe to drive or if I should park it until I can replace it.

 

Yes, they are structural. One of the stronger parts of the unibody

 

Alright I'll have my buddy look at it, he does frame repair for a living so he'll be able to tell me if it's still safe to drive and he'll probably charge me $100 dollars to weld some tubes in. They're not large...yet.