I changed my microwave/convection oven myself. find out the part number and do a search I found the exact replacement at Home Depot and got free shipping. I would not bother changing to out side vent. I just open the vent in the ceiling and turn on the fan on the vent and on the microwave.
Bill
2008 Newmar Mountain Aire
450 HP CUMMINS ISM
ALLISON 4000 MH TRANSMISSION
TOWING 2014 HONDA CRV With Blue Ox tow bar
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain