I can tell you for sure that a 9mm or .38 Super slide works fine on a .45 frame. All you need to do is swap the .45 ejector for a 9mm ejector and use a 9mm or .38 Super magazine. I don't know about the reverse of that, but I would bet that there is no difference in frames, other than the ejector, which is very simple to swap. Just punch the retaining pin, pull out the .38 ejector, drop in the .45 ejector, and push the retaining pin back in. Actually, the retaining pin is not needed, but I use it anyway. My Colt .45 frame is used for .45, 9mm, .38 Super, .400 CorBon, and .22. The .38 Super barrel works fine in a 9mm slide, but .38 Super magazines are unreliable for 9mm cartridges. All the above applies to unramped barrels and standard GI-type frame.
I did have to do a slight bit of fitting to get a 9mm slide to fit the .45 frame smoothly, but it didn’t amount to much, just a few minutes with a rectangular needle file. Also, you may need some different recoil spring weights.