‘82 C3 ECM swap with ‘84 ECM 

The 1982 ECM was a one year only. It was weak and had many programming flaws that GM improved with the 1984. With the 1982, you couldn’t even do an intake, a cam, or most other performance upgrades. The 84 allows it. Lastly, there is an abundant supply of 84s out there if you ever need replacement. 1982 is nearly impossible to find.

The harness is the same for ‘82 and ‘84. So if you have an ‘82, it will plug right up.

I swapped out the whole unit. So now my ‘82 has an ECM and prom from an ‘84

I found mine on eBay. Just have to make sure it came from an Automatic car.