I’m re-powering a ‘99 400ss that had 502 mags with complete drop in take out ‘02 500EFI’s. Both sets of engines have 10 pin engine harnesses but there seems to be differences in the 502 engine harness pin wiring colors and functions compared to the 500EFI’s. I have the original 502 engine serial numbers, and the replacement 500EFI engine serial numbers (apparently originally from a boat with HP transom assemblies and no electric trim senders) but I’d like to get a 500EFI engine serial number from one that originally came in a 400ss. I want to take all three serial numbers to the local Merc guy so I can compare OEM engine harness part numbers for each engine to see the differences. If anyone has a 500EFI engine serial number from one an originally installed in a 400ss they’d be willing to share let me know. Thanks.

Got this figured out so all set. Thanks.