The 26-27 tubes have the square firewall mount and few other subtle changes, but RMT is correct that it transfers the torque from the gear quadrant to the pitman arm. A lot of guys make comments that those two years are prone to cracking in various other parts as well, like engine blocks, and trans drums etc. The tube I can see, having some extra front weight and balloon tires grinding against more paved roads than dirt, but Ive never had a failure. All 15 of my Ts were the improved models, and never had any of the above mentioned failures.
TIG welding is fine, but stitch welding with a mig is just as good. Theyd both need to be dressed and painted. It really wouldnt be that much more to just replace it altogether. That's on this winters bucket list as my wheel has almost 1/4 turn of slop in it. Maybe the wrong gears or just wore out... need to do some research on that issue.
Also, a weld repair is only as good as the prep job. The tube will be rusty on the inside and contaminate the weld... that's another box-o-noodles. ws
