Temp Sender unit question

[Pat Leask <pleask@shaw.ca>]

I have a 1973 TVR 2500M that uses the TR6 motor (Hence the question to you all)

My TEMP gauge is a SMITHS and is in Celsius. My "normal" operating temp is 
showing as a 138 degrees C which is off course wrong.  I'm told that there were 
two (or more) types of sender units.. one in F and the other C.

My MOSS book only shows one for the TR250 and one for the TR6 but does not say 
if it is C or F ??

Does anyone know if there is a C sender unit ? Or can help ?

Thanks, Pat
Victoria BC