Sorry for your bad luck. Yes, I think you should have arc welded it. I'm guessing you used the factory T-bolts ? You can go with 7/16 NF U-bolts. Factory set-up on 68 and up (all the way to 1981) is one U-bolt and two T-bolts per side. A lot of people go with two U-bolts per side. Some even go with 1/2" NF U-bolts (drag racing, mostly). Frank.