I used to love to see the Chessie System locomotives as a kid in Northern Kentucky, usually on the C&O bridge going over the Ohio River into Cincinnati. The "disco" paint scheme was quite a change from the old standard blue with either a Capitol Dome or C&O for progress on the nose. The Chessie had tons of GP40-2s, so when I found one of the Athearn Genesis models with DCC and sound for a great price I grabbed it.
#9120 (originally #4120) was re-numbered while on short term lease to the Santa Fe. Since I was going to re-number it anyway I didn't care what the number was. However, since #4120 had the larger, bolder B&O on the cab side, and since I wanted to keep the B&O, I was limited on which number I could use. I decided on #6022 because it had the bold lettering on the cab plus it had the small CSXT insignia underneath it. Most of this class were simply patched before they were re-painted by painting over the old numbers and applying new ones. The paint was rarely the same color, usually a lighter shade of yellow.
Here is a photo of the original model from Athearn:
Since there are door latches and such under the numbers, I couldn't just sand the old numbers off. To remove the numbers, I carefully applied 91% alcohol with a small brush. After 5-6 applications, I used a Q-tip to gently start rubbing the numbers off.
Once the majority of the numbers were rubbed off, I made one more application of the alcohol and cleaned it up with a paper towel.