Since I have the calipers out for the other question, and was working on this old Rivarossi car...
(facing the car side)
Oops, I see Rasputen beat me to it. I get about the same width, a bit less height... but I lost my N scale level, so hard to say if I really have the steps level.
The measurements on mine are 4.6 mm wide, 5.1mm high, about 7.4 mm deep (that last is +/- because the coupler pocket gets in the way of the caliper jaws).
Note that if used for Rivarossi or Lima cars, the 4.6 mm width looks a little narrow under the door. And on mine interfere with truck swing on anything less than about 15" radius..
Other options that may work better would be Lemosteam's upgrade kits; or, chopping the steps off a MTL frame.