Mustang
It's handy to know some about the Mustang, as it's a good spare parts donor.
First, the 5.0 HO 84-85 Mustang with 5 speeds had a 4V carb instead of CFI.
The 84 Mustang's engine with AOD and CFI was the same as the 84-85 LTD-LX and Police.
The 85 with the AOD and CFI still used the old flat-tappet lifter/cam while the 5 speed got the new roller cam with Stainless Steel tubular headers.
But the 85 AOD CFI also got the new headers which upped the HP to 175 from 165.
Also the 85 AOD CFI now used a 3 wire Heated EGO sensor as it was mounted down on the header tube where the exhaust was a bit cooler compared to the old single wire EGO which was up on the cast iron manifold.
There was no difference as far as the ECC was concerned between the 1 and 3 wire EGO. There also doesn't appear to be any difference between ECC's among any of the 5.0 HO, CFI and AOD's.