Chosen Solution

If I buy a new one, which models should I buy in order to install it on the existing clamp. Because existing one is 1.8 cu feet, can I buy other dimensions , if so will it fit existing clamp. Can someone suggest good microwaves that fits existing clamp.

Measure the dimensions and take those to your local appliance dealer along with your tape measure. The 1.8 cubic feet is an internal dimension, not an external and models will differ.