Thermostat Housing bolt

[Kelving]

Hi,
After taking off my thermostat housing yesterday and I have managed to lose one of the bolts.
I think the size is 5/16x 1 inch UNC. does anyone know if that's correct before I order 1. I have ordered a new thermostat (e2103) which I'm told will help control overheating and is common practice for a Chimaera 4L pre serpentine.
Thanks Kelvin

[phillpot]

Measure one of the bolts

Most likely unc if threaded into alluminium, that'll be 18 threads per inch if it's 5/16" diameter, unf is 24tpi so a very clear difference.