What is this? Photo eye??
 

On our 83 Chev, mounted next to the speedo on the back of the inst. panel, there appears to be a photo eye mounted. It is held in with one screw with 3 wires going to a yellow box. Is this part of cruise control? If so, can someone provide pics of cruise/turn switch and under hood components?

how about a picture of yours?

That is your VSS (Vehicle Speed Sensor) The truck uses the signal it produces (2 pulses per speedometer cable revolution) to tell both the ECM how fast you are going (ECM = Electronic Control Module, basically the computer in the truck, ECM will be found on feedback carbed trucks, and is that silver box behind your glove box) and in some cases, is used for running the cruise control setup (not 100% sure about the 82-86 trucks, they may have a transducer style cruise setup yet...)

Yes that's the speed sensor for the cruise.

Anybody have pics of a working cruise setup? The truck was in pieces when we got it. I would like to know what to look for to get the cruise working.

I gave up fixing the cruise on my 83. Instead I installed a cruise control from www.rostra.com.
Read about it here http://www.geocities.com/abetterchemist/cruise.html

I have a working cruise on my 86 Sierra. I have some underhood shots of the truck, but it looks like the air cleaner and brake booster are blocking the parts you want to see. If I can get my hands on a digital camera I'll get some shots of the underhood stuff.

Many, many thanks.
gchemist- how much was the kit? I went to the Rostra.com site and they did not show a kit for my 83?

Oh, by the way:

If one of you guys has the chance, can you snap me a picture of the order that the wires go into the green box? There will be a black, pink and black and yellow wire, I had to remove the pins from mine and I cannot remember the order anymore...