what do i do about this?

sooooo turns out a corner of my roof is bondo? how do i patch this?

Cut it all back, weld in some new metal. Skills needed. It you don't have, pay a good body man to DO IT RIGHT, Don't just patch it up with more mud or you'll be sorry.

yeah thats what the last guy did i think (smells like bondo at least) i dont even know how it could rust there to start with?

It's the roof to pillar joint..A known bad spot on these cars due to stress flexing of the unibody..The real way to fix it once & for all requires removing the windshield..the trim..drip rail molding. The roof joint overlaps onto the pillar & the windshield flange..you need to melt the lead out of the joint to see it..after you replace the metal you FULLY WELD UP the joint not a few spot welds like the factory did. Sorry to be the bearer of bad news but any other method will fail after time..Unless you do the above it will be back..

well the big block probly dont help the flexing, my dad does alot of fabrication and machine work i think its time i call him by the house XD at least for this

Thanks for the heads up. I'm restoring a '71 now and I wasn't aware that there was a big problem with the front roof pillar joints. I was planning on leading the 1/4 seams when I replaced the 1/4s anyway so now I'll melt the lead in the front seams too and re-weld those joints. THANKS FOR THE TIP.