Foooz1

I need to replace the frame rail that is directly behind the cowl under the drivers side floor pan. I purchased the front frame rail patch (M122) from CJ however it does not extend far enough towards the rear of the car. Also this piece appears to come over the top of the existing rail whereas the existing rail is rusted away on the bottom. Looking at the pictures of the complete frame rail at CJ it also appears to stop short of where I need to replace.
1) is there a different name for the rail under the drivers floorboard behind the cowl and if so what is it?
2) does anyone have experience with how far towards back of car the complete frame rail from CJ extend?
3).where can I find the piece needed to complete my frame?
Scott