[Mr70]

Neat lil piece..That's a valve body pressure switch.
Used on nearly every Gm vehicle with an Auto. Trans.w/rear wheel drive,from 1976 to 1990.
Ones that used it in the Chevrolet family were Camaro-Nova-Impala-Elcamino-Malibu-Monte Carlo.
I don't know what you want for it,but I'm seeing multiple dealers having it in stock for $20-35 today,if that helps any.