Thanks Don, it was a huge wake up call I walked away without a scratch after spinning through 3 lanes of peak hour traffic at 100 Kmh, at the time I had it on cruise control sitting behind a cop car chilling...
Looking at the arm it looks like a fatigue crack that just had enough...
Those 2 arms were the only stock parts left in the car so I guess 10 years over 400+ rwhp took a tool not to mention the 300,000+ Km's I'd put on them.
I've moved on so don't think I'll ever be back in a Supra but thanks for the offer!