I was about to be like "surely you mean the S/390 series" but nope, you are correct! Apparently 3090 came in between the S/370 and S/390 series: https://en.wikipedia.org/wiki/IBM_3090

I remember! My dad had an extra 3090 metal badge (maybe 2–3× the size of the ones on PCs) that we had glued over our XT's badge for a while lol

You are right. I used to work on one. Yay COBOL.