Broken Diff
Just to update this thread for those interested.
New diff centre is a spooled 741 case 3.73 ratio.
Trans was removed and the sprag WAS hurt.It was replaced with a Coan Engineering supersprag.The trans was otherwise perfect.
The car has since done another 30 odd runs and on Saturday night(a cold one for here) it dropped to 11.9s in the 111s with 60s from 1.62-1.69.
Gotta love PBs !!!