Quote: The "original MGA" book says mine should have an SU AUA 54
When the MGA was new, the same pump (AUA 54) came in nearly a dozen different designations (I am exaggerating, but not by much). Today, the pump you are looking for is the AZX 1331 as a standard points style pump or an all electronic pump it is a AZX 1331EN or AZX 1332EP. All three pumps look exactly the same, which is the sway they looked when the MGA went into production. Moss sells the points style pump under P/N 377-042. The solid state negative ground is P/N 377-225 and th epositive ground version is P/N 377-235. All three pumps look exactly the same other than red tape around the end cover-body junction for the positive ground and the negative ground (and the points style pump) have black tape around the end cover to pump body junction.