IF your Thunder is same as our 2004 Marquis we had a GE Convection microwave, in Black. Due to the year it did not have the ability to bake a cake, etc, so we changed out to a newer GE Convection in 2014, Black. In 2015 we redid the interior of the coach and then again 8 months later we changed out the Black to Stainless to match the new Samsung Refrigerator.
In 2017 we purchased a new Entegra Cornerstone which came with a Whirpool Convection microwave. The wife wants the GE back as she states it is much easier to operate.
Now to do any of this was simply unplug and loosen the 2 bolts along the top front on the microwave. No carpentry necessary. Round about way to answer your question but gives you some info on differing units. I will soon have a slightly used Whirlpool Stainless Convection microwave for sale.