I think you need to clarify that "flare fitting" part, didn't the 216 years all have mechanical gauges with a threaded bulb on the end? a flare fitting is for tubing with a flare on the end for sealing liquid .... any temp sender I've ever seen has standard brass pipe threads and will fit various brass plumbing fittings .... maybe you're actually dealing with the oil pressure gauge?

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot