92 Thermostat bolts?
 

I have a 92 s10 Blazer and I need to change the thermostat, only problem is that I cannot for the life of me figure out the size of the bolts to remove the upper radiator hose to actually access the thermostat, I've tried every standard and metric size I have. Could anyone please help me out?

I thought they were 13mm? il check tomorrow.