Thank you for the great information. For those interested I did finally find this excellent post with pics on how to remove the unit.
http://www.clubsearay.com/index.php?threads/sb400-2003-microwave-removal-replacement.86567/
Yes, Thank you. That was one of my reasons for posting and asking if it can be done. I understand the convection units produce much more heat. The cabinet it’s in now has vents in the top but I’m not sure if that is enough.
I have a 1999 400 SB and would like to replace the existing microwave (Panasonic Genius Premier 1100 model #NN-S569) with a new microwave convection unit.
Do any of you know if this is possible and if so what brand/model would fit in the existing microwave cabinet?