well, the 1 1/4 is too small, and the 1 & 5/16 is a little larger than the 3/4W. The only one between the 2 is 32mm. Shame I don't have any other deep sockets. It's probably something wierd - hence the churchill tool.
Well, I have ordered a socket from ebay.
The thermo housing is now toast. I will have to cut it off the head and get the engine man to get the remains of the studs out.