Actually I was able to leave cross member in place... I took out 6 and 2 would not budge but once I removed the. Collector side to main muffler the y pipe sat with cats just behind cross member on the pipe itself leaving plenty of workspace ... A little shimmy here and there and all slipped right back into place almost effortlessly compared to the effort of drilling that flange bolt out... Lol that was PITA but strait forward...

 

here is what I removed from passenger side... Im still getting P0150 code even after ultra gauge reset codes.. also O2 sensor starts out .445 or so and after about 20 seconds switches normally then goes to basically 0.000 and stays there... I removed the 2 month old O2 as it was also reading 0.000 on passenger side so I took the older one and reinstalled it and it worked better... the new one I had put in last month was gunked up with black soot from running rich on that side... since the old one started working nice for a few minutes before fouling out, Im assuming it was bad anyway but dried out for a few months ... but fouled out somehow... maybe I should buy another new O2? I dont throw any codes except the P0150 and now I have new y pipe gaskets...

 

Believe it or not, your gasket doesn't look half bad. The ones I removed from my truck had the whole center section cracked/broken.

I do see the black soot you're referring too. Can you smell it in the exhaust?

Where did you purchase your O'2 from? Have you tested them to see if they are faulty? There's a procedure you could follow to test them where you send a concentrated specified amount of heat from a torch.