tothemax, your missing quite a bit of structure thats going to allow flex in the bar and eventually lead to cracking/breaking. higher hp trucks will speed that process up significantly. welding those two peices of flat metal in a butt joint style with no added support and you created a fracture point. only relying on that 1/4 thick strip along the bar for the actual trans mount will work that bar over when abused as well and start to tear the weld at the tube. specially if someone runs a poly mount.
dont take that the wrong way, you got a good idea, it just needs some improving before id sell it on here. add a few more gussets at the ends vertically that rest against the frame or bolts to it as well (that would really strengthen it) and make the that little 45* piece you have supporting the trans mount the same width as the actual angle iron (or both pieces longer even), make those flat tabs 1 piece and you have something that should hold up well providing the tube wall is thick enough (i would prefer chromoly in this instance but i like over building