Test it on land. Does it close tightly, without binding? Does the camera fit solidly, without rattling? Does the lens extend fully without hitting the port? Does the flash line up with the flash opening? Does the shutter button operate on half and full press? Can you access all other controls that you normally use? If so, it works. There may be a slight difference in controls or fit that required a second housing for the two models, but if you're happy with the fit and control access, and the case doesn't bind on the camera or deform when installing or closing, it should work. Only way you could tell the difference is to hold the two housings and cameras side by side and maybe take a caliper to them to see if one is a millimeter deeper or something. In the old days, they used to make one housing to fit all SLR's, and you just changed the mounting plate and some of the button extensions to use different brands and models.