A Line Mechanic was informed by his Maintenance Manager that Quality Assurance had discovered there was a discrepancy with the Part Number of the Flight Data Recorder (FDR) he installed and Signed-off. The FDR was not the correct Effectivity number for the B737-400 he worked. He had relied on another Mechanic to verify the Part Number.

Narrative

I was working on a B737-400 at ZZZ; on a Routine Overnight Maintenance (RON) check. Myself and two other mechanics. We had several tasks as well as an MEL for a Cabin Pressurization problem. One Mechanic had gone to retrieve parts that were pre-drawn from stores. Mechanic came back with a Flight Data Recorder (FDR). Reading over the Job for that task; there was some confusion over some of the steps. I went on with one of the mechanics to complete the other tasks on the plane; due to aircraft had a early departure. At the end of the night I was told by one of the Mechanics I was with; that the (part) was the right one; so I installed it and Stamped-off the job card and turned over the paperwork to be entered into aircraft parts history computer.I was notified by Maintenance Manager that Quality Assurance (QA) had discovered there was a discrepancy with Effective Parts Number installed. I believe it was caused by a lack of communication. The Job Card was confusing and I should have verified the information myself. Also we were pressed for time.ZZZ1 was informed by Maintenance Control to verify the Part Number of the FDR installed and if not correct; to replace. They found incorrect Part Number was installed and installed correct one. I should use all resources to clarify any confusions about paperwork and verify the information myself.