I'm replacing the battery tray in a 1997 4.3 4x4 and under the battery tray is a part that has an electrical connector going to it and a cable routed beneath the truck.

It looks like it might be some type of diaphragm device.

Can someone identify this part?

Thanks.
Al

 

Sounds like you are describing the front axle actuator for the 4wd. It is not electronic, rather it has a vacuum line that would be routed down to the transfer case vacuum switch for activation. The other end goes down to the front axle.

 

I took a closer look. You are correct.

What I thought was electrical connection protected by split tubing is a good sized vacuum line.

I should have looked a little closer.

Thanks again.
Al