When you say "24' Cheetah" do you mean Stiletto of Deck? If you mean Stiletto than Aqua Performance is bout your only choice. The bottom of the swim step is at an angle and Aqua Performance builds a unique step only for the 24' Cheetah Stiletto. I cant remember if its longer than the standard step or if the steps angled end is modified.
Aqua Performance (http://www.aquaperformance.com/boatsteps.html)
Call them and tell them what you got for the right step!