Does anybody even installed an air/fuel mixture gauge like this before ?

http://www.glowshiftdirect.com/index.asp?PageAction=VIEWPROD&ProdID=187

I have one like that in my Firebird. It hook's into the o2 sensor. I don't think it'll work with a diesel?

that's exactly what I was wondering ?..

There is no need to meter the A/F ratio on a turbo diesel and is pretty useless. Diesels are not "throttled" so there is no mixture of the A/F before injection and the air isnt metered. A modern TD is always gulping as much air as it can for a given RPM so all we are doing is adding fuel. You can add as much fuel as you want and it will still run. The more boost you run the more fuel you can add and even over fuel it. Thats why you see a lot of black smoke. As long as air is being forced into the combustion chambers you can just about pour any amount of fuel into it. This is why stoichiometric efficiency is a topic of heated discussions when talking about turbo diesels. If you were to install a Lambda sensor and try to read the A/F ratio it would peg the needle when you put your foot in it. You could see as much as 40:1 at cruise speeds and 3:1 at idle.