front frame rail replacement help

have most of the front driver's side frame rail out except for where it attaches below the firewall next to the torque box. basically i just want to know what I have to drill out and cut to get it out. I can see the spot welds I need to drill out but my question really refers to the area the frame slips into. Please refer to my childish drawing below (particularly the area circled in green). Sorry for the crappy pic but it's all I could find on the internet. Thanks
View attachment 412697

lauras70mach1 said:

Yep, to do it right you should remove the torque box and frame extension. That's a big job - did you level out the car and take measurements I hope?

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took detailed measurements over and over again and I leveled out the front end before cutting ANYTHING! I was just hoping to get away with not removing the torque box. Thanks for your help