Odd that it was removed, a piece of black tape does the trick. I don't know the number or where you could get a bulb other than "borrow" one from a less important circuit. If it' 2 wheel drive then you don't need a service 4 wheel drive light. Does the inspector require a seat belt light?

 

You sure it is a diode?

 

He's probably talking about the light-emitting kind of diode. ;-)

Have you removed the cluster, opened it up, and actually tested the LED to see if it is actually faulty?

 

Post the photo of the top/bottom side of the cluster printed circuit board. Then we'll see whether it should be a diode or a regular, small size light bulb;
The light bulb has a filament inside, that will limit the current flow, while LED doesn't[1]. If You put a LED into a light bulb contacts, it will get instantly burned. Putting a lightbulb into the led contacts will make it just glow.
If You're sure it's a LED You may get any of the LEDs with the orange color, that will fit. I can't take measurements now, but I guess 5mm should do the job. The LEDs aren't expensive, so You may even get a bunch of them and waste on tests.
Beware, the LEDs are directional, so with one polarity they emit light, the other one they don't.

[1] There are however the LEDs with a current limiting resistors, and amongst the catalogs they are described as "12V LED".

 

 

 

I'm happy for you that it's 4 wheel drive, missing led not so much. Looking at the back, can you tell if it was removed with heat (soldering iron) of broken off? Since we need to pass inspection the light must come on and then go off. Are there any codes?

 

Good job!
Yes, these are diodes, and You do have the resistors for limiting the current. 5mm diameter fits. You may pick any of the color You like (unless the front plastic is transparent, then You'd like to have a yellow one). While soldering pay attention to the cathode mark (flat part of the circle). The LED case is going to have a same mark with a flat surface.
You shall get them with any nearby radio shack, recover from some other equipment or buy. An example link:
https://www.newark.com/w/c/optoelect...lts?st=led+5mm
(they're pricey, I am giving the link in case You run into troubles finding them).

 

I concur with Mike's assessment. As he said, notice the flat side to the LED body to help orientate it properly in the board. You'll notice that the outlines have a flat line on the otherwise circular marking. Are you good at soldering? If not, look at some videos on how to solder to a printed circuit board (PCB) and learn what a "cold solder joint" is and how to avoid them.