I don't know for WW2, but in the 50s/60s the USN definitely also had blocks. At that time blocks were visually applied by small letters after the BuNo, beginning with A up to Z and then starting with AA and so on. I spent some time in the past, looking for those for the Skyhawks, but it seems, it's not entirely the same blocksystem as the one from the USAF.
USN-blocks seem to be small production badges of planes. For A-4Ms for example the productionblocks were like 12-13 and up to 24 planes (158 planes made in blocks A-J). On A-4Cs the blockletters reach up to AA or AB. Unfortunately I couldn't find any references on what the actual differences on different block letters were.
Those letters were also used on other USN planes (F-4, F4D for example), but not for a very long time.
Sorry for the hijack.
Thanks for the input on F-16 blocks.