I've got it racked up so don't want to pull it back out for pics, but to the rest of your questions:Could you post some pics?
Also, where did you source these from? I found the Mechatronics only at digikey and the Sunon at Mouser - not both at one. Then again, I do have some parts I have to get some Mouser anyways...
I purchased the Sunon from Mouser and the Mechatronics from Digikey - just as you said. Agreed - it's lame they aren't both at one...but it beats getting knock-offs.
So far as mounting the Sunon, just place it on top of the existing heat sink and put some screws in the pre-drilled holes on the Sunon wide enough to grab onto the heatsink. There's probably cleaner ways to do it but it's very secure. For the 48P you may need to angle the fan slightly to avoid the Molex on the PoE board, but it'll fit.