2019 Mac Pro Desktop 7,1 Downgrade from 1TB dual module to single 512GB. Why? Have a spare.

Using: Mac Pro desktop 6,1 running stock Monterey. You DO NOT need a later OS unless you are using Finder instead of Apple Configurator...but I have old machines so I'm using "AC". (Apple Configurator.)

FIRST: Use your Mac Pro 7,1 to download Apple Configurator FIRST FIRST FIRST. Did I say first?

Use the same Apple ID you're going to use on the 6,1 Trashcan

Once you download it on the 7,1 the App Store will offer to let you download an older version.

Doing this as we speak so bloggin in realtime.

Also A new thing you want:

PCIe SSD Adapter from Amazon: https://amzn.to/4dDzRTA 

This has a HONKING huge heat sink and users report wildly lower temps. Further, you can use Apple NVMEs it appears if you have a 6,1 or other Apple NVME. Just buy that version obviously: https://amzn.to/4fh3tra

Not sure if that version has a heat sink.