From my experience it will depend on the width of your door.. My old Passport had two doors... the forward door which entered just outside the bedroom which had a 3 step and the rear door which entered into the living area.. which had a 2 step..
Since we almost always used the rear door I had the bright idea that I'd order a 3 step for it...
So..... I measured the 3 step and ordered another just like it... Yep, you guessed it... didn't fit the 2 step mounting area.. Measured the 2 step and couldn't find a 3 step that would fit...
Still got the new 3 step in my garage at the sticks & bricks...