I have the Ikelite Underwater Housing 6871.40 for the Canon 400-D (Digital Rebel XTi)...will the housing work for Canon Digital SLR 40D? Will it partially work?

Any information would be helpful!

Thank you!

The bodies of those two cameras are very different in size and button positioning.

I do not recall anyone mentioning trying that adaptation..yet.

Though of course it does not mean you cannot try to see if you can get the shutter pressing.  I think all the housings for the Ikelites are often generally the same body with the controls moved around which is how they turn them out so quickly after a camera is released when compared to other housing companies.