What is this part

[louiswp]

On my 95 sierra 4wd left side bolted to the inside of the frame by the brake lines near the forward cab mount.
94 2wd doesn't have it.
Air bag sensor?
Part number is not clear enough for a search.

You must be registered for see images attach

 

[Steve A]

Appears it might be a Vehicle Speed Sensor Calibrator, in GM lingo.

 

[louiswp]

I see it has 2 more. 1 on the frame in front of each tire and radiator support.

 

[chipskittles]

Those really really sound like air bag impact sensors. The yellow connectors are a dead giveaway.

 

[skylark]

Impact sensor. That rust is crazy!