What is this?

[WE4Turbo87]

Hello, I just bought a 87 WE4. It only has 10k original miles. It has this box mounted under the radio. Does anyone know what it is? Thanks

 

[pacecarta]

looks like a knock gauge

 

[THensley]

and a ALKY light to the right

 

[1986 Buick GX1]

As mentioned it’s a knock detector.
The green light indicates it’s ready for use. The red lights record how many knock events occur, usually through the 1/4mi.
The red lights accumulate from left to right and stay lit while the green light goes out (I think).
It will reset after 1 min or so to give you time to look at it, the red lights will go out and the green light comes back on telling you it’s ready for use.
They used to say 4 lights were acceptable during the 2-3 shift, but any more than that was bad.