I tried to fit a rear step on my mn. I was told that the mn and ml are the same but It wouldn't line up and fit because of the tow bar. I was told that the there are different tow bars. Before you buy a rear step bumper check if it fits.
I too was told that the shassy is the same but the rear tub is longer. But then again I would like to know from someone who works at a wreckers and pulls apart these vehicles often.
The rear chassis are the same The rear steps are the same as well BUT There are different brackets that suit the ml and mn and make it fit the different tub lengths
Also the factory towbars incorporate brackets for the rear step, so quite a few factory combinations to get the rear step to fit, these will not necessarily fit with aftermarket towbars