Had my '73 done when I bought it five years ago. There were no cracks but $100 to the "hitch guy" had side gussets mig welded on both sides. Cheap peace of mind!
What I have found however is that you need to keep an eye on the bolts that hold the fg to the frame. I had mine replaced last year but a low gas station entry ramp bent them both severely.
This time I used humongous carriage bolts and ss washers and reversed the whole shebang...heads of the bolts outside...nuts and lock washers inside. Nothing to catch and rip on those nasty concrete frame-wreckers.
FWIW, I think the Transport Canada recall only applied to the first few production years - the factory stopped heat-treating the metal after that.