I have an an LM1 with an A/F gauge in my Duster so I am familiar with them. I got a wide band, not sure if anyone even makes a narrow band these days? It's an Auto Meter Cobalt, a digital stepper motor type.

When I was looking, I found that Summit sells a clamp/band thing that you wrap around your exhaust pipe which has a bung built into it. You just drill a hole and put the band on where the hole is. No more muffler shop!

Going to make a mount panel for the gauge in my dash where the radio was.