That model has been used in RVs for at least 15 years. It has to be the oldest running model of microwave ever, HA! Anyway, you should be able to jump on amazon and find it. However, I might look at convection microwaves. There is one (I don't have the model right now) used in the big motor coaches that is the same size as the Magic Chef microwave used in most campers. It is a few dollars more, but does give you some extra functionality.
Current TV:'14 F350 Lariat CrewCab, 4x4 Short Bed SRW Diesel w/ Pullrite 2700 (16K)
Current Fiver: '15 Puma 295BHSS Anniversary Edition
Past TV: '13 F150 HD Payload SCrew EB, '08 Tundra CrewMax 5.7L, '02 'Burb 5.3L, '97 Dakota 3.9L
Past Trailers: '09 Wildwood LE 27RB, '02 Palomino Yearling RL, '87 Jayco 1006dlx