Most minis with dual gauges up to 1969 including Cooper S Mk2 with oil and temp gauges fitted used this sender when fitted with a voltage stabiliser.

Minis before Sept 1964 except some super deluxe and pre Sept 1964 Cooper without voltage stabiliser used GTR102.

After 1969 use GTR101.

Another guide is that the gauge for this had a pointed bezel but if you have the later rounded bezel type from 1970 on try GTR101 if readings seem wrong.