I did a quick online search but was unable to find any reference to an alternate Sea Wolf PROM that I have. This one is number: 27S81DC-0069, and replaced 27S81DC-0042. Location 1G. No other PROMs are different.
No idea what it does differently as game play appears the same, and I am also having trouble reading/archiving the PROM. Have tried alternate PROM settings for my Data I/O 29B including Signetics 82S181 or AMD 27S181. I get garbage, same garbage with other known-to-be-good PROMs, same settings. I will read the darn thing even if I have to make up a cheater socket.
Most likely an update to the code, however it does not 'fix' the slight bug where if DIP Sw #8 is not on when either #6 or #7 (or both) are not on that the game freezes up with just the water line showing.