Air carrier Maintenance Controller reported they advised Maintenance to install an ADIRU that was later found to be an incorrect part.

Narrative

ZZZ Maintenance Person A called parts personnel that they are replacing the left ADIRU (Air Data Inertial Reference Unit) to resolve an issue. They removed P/N HG2050BC06 and they have P/N HG2050BC04 on hand. He asked if it is OK to install the P/N they have on hand since IPC (Illustrated Parts Catalogue) 34-21-01-01 in confusing. IPC states 'HG2050BC06 can replace or be replaced by HG2050BC04 with 2015 MAGVAR (Magnetic Variation) activated or requires incorporation of SB 737-34-4248 (activates 2025 MAGVAR)' Note that the aircraft has less than 1 hour left to departure to ZZZ1 and after doing some research; I determined that the we made a change on the 737NGs per EA (Engineering Authorization) XXXX-XXXXX to upgrade from the 2005 to 2015 MagVar. Also; SB 737-34-4248 is not applicable to this aircraft since this SB was incorporated at production; which would make us Post SB. With how the IPC is worded; that means that yes; we can use HG2050BC06 or HG2050BC04 and there are no intermixability restrictions. Hence; I advised ZZZ Maintenance that it is OK to install P/N HG2050BC04 per IPC 34-21-01-01. I kept researching and later found when the aircraft was in air and on its way from ZZZ to ZZZ1 that since SB 737-34-4248 was incorporated at production; we cannot use HG2050BC04. This is because ADIRU P/N HG2050BC04 only has the 2005 and 2015 MagVar Tables and P/N HG2050BC06 only has 2015 and 2025 MagVar Tables. This means that if the A/C had HG2050BC06 installed but was pre SB 737-34-4248; then both P/Ns HG2050BC04 and HG2050BC06 are interchangeable and intermixable. The current wording in the IPC is misleading. While the aircraft was in air from ZZZ to ZZZ1; I called Maintenance Control and adivsed them of what occurred and asked them to stop the aircraft in ZZZ1 and have the left ADIRU replaced with P/N HG2050BC06 prior to further flight.