It is correct. The 24-600 takes the large tube. The 24-603 takes the small tube. Ck your watch, it most likely has the small tube, which means your 24-603 will fit. However, If it is the large tube, you can only use the old 24-600 crown. You can go up in size with your case tube, but you cannot go down. That said, I have repaired ladies cases, using a large case tube. Here is how I did it. I drilled the ladies case, which has a small case tube, larger to fit a large case tube. I installed the large case tube. I used loctite to seal it in the case. Once it was installed, I then tapped the case tube with a ladies tap. After I tapped it, I cut the case tube flush with case, cleaned it up and put a small taper in it, and installed the small tube. It was a water tight fit. I don't recommend it, unless it's not repairable any other way. It was very nerve wrecking on the ladies gold case. A couple of AD's in town said it was not repairable. It was scary doing it for the first time. But, it worked and saved a $2500 case. You really couldn't tell anything had been done. I guess I was lucky.