Chosen Solution

I just bought an early 2009 Mac Pro (4,1)  running High Sierra, but discovered it had no WIFI, which is vital for me as I live in a Mobile Home with the Mac in a different room from the wireless router. My 20” and 27” iMac’s  WIFI works fine from that room. Apparently, the Mac Pro was patched to appear as a 2010 (5,1) model, but still WIFI is not recognized. Can anyone point me to a compatible WIFI card as I have tried every card I have in my repair part storage, including external a USB WIFI and none are seen in setup.

You’ll need to get this WiFi adapter: AirPort Card 661-4907 The Intel board does not offer the needed drivers.

Just finish install, best solution: https://www.osxwifi.com/product/mac-pro-