My 89 GT has a thermo sensor at the bottom back of the radiator on the passenger side. (pointing towards the block) When one of the connectors broke off mine a couple years ago, NAPA had the part. I recall it being $15 or less. $55 is a price that earns the designation "Stealership."
1989 MX-6 GT. ORIGINAL OWNER!! 322K miles on the original clutch, K&N drop-in, Gillis boost valve, Tokico Blues, OEM RSTB, Energy Suspension poly sway bar bushings, end links, OEM rear lower tie bar, PGT rear sway bar. Techna-Fit stainless brake lines, AWR trailing links, new OEM lateral links.