NefMoto

I know this is a total Noob question but here goes. I want to purchase a “spare “ ECU to practice on so I don’t brick the one in my car while learning. What do the letters refer to at the end of the part number. Specificity an ME 7.5.5 . My car has a 8N0 906 018 K can I flash the map from it to a 8N0 906 018 L for instance. Is they letter just what program is in there? My assumption is as long as the base part number is the same the letter is just a mod to the program. There are allot of used ECU’s out there and the prices very allot. So trying to figure out if I can buy a S,L,AN or whatever and reflash it with no problem.
Is there a reference somewhere the shows what the different letters refer to.
Thanks in advance.

Different letters could mean things like different gearbox set ups and that though, or even the same letter but different software revision can mean that, or the difference between one ecu running narrowband and one wideband, one a K03S turbo and one a K04 etc.

If you can find out if the ecu or car set up for that specific ecu matches your's pretty much the same, then usually a lot of them can be crossed flashed. I cross flashed a Tiptronic file to my manual once to see if it would work (AUQ), it did but I'm pretty sure there were some changes the ecu didn't like, so I didn't leave it on for more than a couple of minutes, I just wanted to know if it would work!!  ;D

In general assume that ecus cannot be cross flashed unless known to work. There are threads on here that list known good combinations.