Someone posted a few months ago and said that when US changed computer systems (Pacer? AA?) in 1998, the elite members got new membership numbers without any letters.

I flew on the morning of the changeover and I got a handwritten boarding pass on pink paper because the computer wasn't working at PIT.

My DM number has no letters! I was US silver at the time and my number begins with 3. I don't know if golds in 1998 start with 2 and CP with 1.