Well, the good news, this being an A-suffix, means that it has the internal sheetmetal redesign- no foam seals to worry about, and easy access to the blower wheel. The original panel would have been glass with red LEDs but it's now wearing the Amana service replacement panel, so it should have some life left in it.
The very last analog Radarange was the RRL-5C from '84/85. One large timer dial, a start button and a Cookmatic knob for Full/Defrost/Slo-Cook. And it's 100% electro-mechanical. Possibly the most dependable microwave oven ever built.
Around the same time you could also get the RR-700, this was the sleek black and chrome model with vac fluorescent display and a pair of knobs. One for cooking power, the other was an encoder to enter your time on the digital display. Seems like back in the day, everyone in the midwest had that model.