That style is a dime a dozen - you can find them at just about any marine store and multiple places online. Windline, Garelick, Jif, to name a few. It looks like you have room to upgrade to a 4-step ladder if you wanted.
Just replaced mine. Grady confirmed the part number and gave me this number for the Windline supplier. 310-516-9812 They all look the same but best to get OEM part so you don’t need to drill new holes (5 min to install).