If you see on this link there is a picture showing the back of the gauge. I don't know if yours has a 1/4" or 1/8" NPT fitting but yours should look like this one.
GlowShift | Tinted 7 Color 200 PSI Mechanical Air Suspension Gauge
If not please take some pictures of the gauge that you have and post them so we can see.
OK OK I finally got off my duff and went out to the Mistress to check my gauges.....sure enough my 1983 has the same gauges. My speedo had the same T with two blocks on either side, my oil and water had the name Teleflex written in the gauge face.
Teleflex are marine quality gauges so it doesn't surprise me that Airstream used them (although I did have a VDO gauge but I'm not sure that its stock). You can contact this place if you want a Teleflex gauge, HOWEVER even they may not have a direct replacement and you will pay through the nose for it.