I have actually a used Jenn-Air microwave that we got rid of from your house during a remodel. Its works great, we simply changed our home appliances for stainless steel ones.
This microwave is developed to hang above a range, under a cabinet. This microwave comes with a custom-made bracket and good wooden top to hang from a wall without a cabinet above it. It can be mounted either means.
Not sure on its age, I 'd think 8 years of ages.
Works like brand-new.