Finally getting to it!!! 1970 Duster 340

I decided to install my driveshaft yesterday. I was tightening one of the yoke strap bolts to 170 inch pounds when it broke in the yoke. Looks like I'll need to remove the yoke and try to remove it. The problem is that the bolts are only 1/4 inch which doesn't give much surface area. I've had success using my welder on larger bolts to weld a nut on to help with extraction. I thought about cutting a small piece of brake line to sit over top the broken piece and then weld inside to protect the threads. A nut could be welded on top of the tubing. Any input would be welcome.