The 81-184 boards are part of the "Universal" boards. They can be found in the 4X, New 2, ...
This is a closeup of the 4X board. Note that U53 is populated and that U60 has resistors replacing it. This is required for the Drivetec Drives.
This is a New 2 board which does not have Drivetec drives and does not have U53 but does have U60.